Hello There,
with the Cayo Perico Heist being some days old already, I feel like I've gained enough experience to share my method of doing it as fast as I can with you. I'll only cover the missions neccessary for this method and approach, as covering every mission would turn this into a novel.
With this approach, you're looking at $~1,3m every 1:00-1:30hrs, depending on how well the finale goes. Ironically, you get a higher payout when playing solo. Some pretty effective solo grinding.

1. Preperations

Right, so what do you need to grind the Cayo Perico Heist? Not a lot, surprisingly. Obviously you'll need a Kosatka, however, all the extra additions like sonar or missiles are not needed. However, the onboard Sparrow is insanely useful, it's easily worth spending the $2,1m to buy it and upgrade it with homing rockets, you'll get the money back in 1-2 heists anyway. If you get the Sparrow, you can forget about all other vehicles like other Helis, Oppressors or jets, the Sparrow is all you'll ever need.
About the position of the Kosatka, I'd try to leave it at Vespucci Beach, however, you can and probably will use it to fast travel to far away locations for missions.
After starting a mission, turn around from the heist screen and hop directly into your Sparrow (except if you want to fast travel first). When returning from a mission, feel free to jump out of the Sparrow and parachute to the sub, you won't have to pay any insurance and the Sparrow will instantly be returned to the Kosatka, ready to be used for the next mission.
Additionally, a saved outfit with a scuba suit is also useful for some prep missions.

2. Prep missions

2.1 Gather Intel
The most lengthy mission. If you've already completed the heist as a leader, you'll have to steal a Velum to fly directly to Cayo Perico. This is where the fast travel of the Kosatka comes in useful. After flying off with the Velum, don't forget to return your Kosatka to storage so you can call it back later when returning.
Now, what do you actually need to find? Luckily, all the random POI are not needed at all (Uniforms, Grappling Hooks, Bolt Cutters). I'm sure you've seen this post with the map of all the intel. Surprisingly, all you need to photograph is these fours spots, one of them being the sewage tunnel underwater, which only has to be scouted once, you won't have to scout it every heist.
For the mission itself, just grab the nearest bike and jump over the hill on the left side of the checkpoint next to the party and drive to the comms tower. There, hack the security box (box can spawn on ground floor or on one of the 3 tower levels). The hack is fairly complicated, however you can use your training keypad in your Arcade to get familiar with it, you'll have more than enough time at the tower to figure it out anyway.
If playing solo, just scope out the main reward and move on to scouting the main docks for additional loot to fill you bags, as you will not be able to open the houses inside the compound for the loot there as they require 2 keycards simultaneously.
At the main docks, scope out the 2 places for additional loot and then let yourself be caught by the guards to be thrown back to the airport instantly and leave. Thats it, no more intel neccessary, only takes you about 15 minutes.
2.2 Kosatka
For the approach vehicle, you'll want to use your Kosatka, so start the mission, fast travel to the mission and use your Sparrow to deal with the Heli + 3 boats. You can then just dump your heli in the water and request a Dinghy to drive back to the Kosatka to save you the hassle of landing the heli and swimming to the sub.
Inside the sub, go right down the hatch and fight through the lower deck until you find the device, leave up throught the hatch ladder and leave the sub.
Outside, hop into a Dinghy and drive back to your Kosatka and the mission is done.
2.3 Cutting torch
Only 3 of the 4 equipment preps are mandatory, you can completely ignore the explosives as you will be using the cutting torch for any locks you encounter.
The mission is very simple, fast travel back to Vespucci beach, fly to the construction site, either kill everyone and grab the drill or do it sneaky and fly back to the Kosatka, nothing huge here.
2.4 Fingerprint cloner
Another pretty simple mission, fly to the warehouse, go in and be prepared to fight instantly, its unneccessary to cut the power, the guards will spot you insantly anyways. Then hack the computer, fly to the Archives, shoot the 2 cameras, get the cloner, fly back to the sub, done.
2.5 Safe codes / plasma cutter
This mission depends on the main loot, you either have to go to the casino, kill a lot of people and greab some codes off the head of security, no major ways to improve here other than to shoot, as this can't be done in stealth reliably either, and fly back to the sub.
For the plasma cutters, (Actually can't remember the mission right now, must not have been hard then, just do the usual Sparrow, pewpew, grab, Sparrow stuff)
2.6 Weapons
FOr weapon loadouts, you have multiple choices, I suggest either going for the Conspirator or AP Pistol loadouts, they are both very viable and neither has a distinct advantage, use whichever you prefer.
This mission has 2 variants, you either just do the usual "Land on office, enter office, shoot guys, hack computer, get weapons, return to sub" stuff, or you'll have to follow a Merryweather heli, kill some goons, enter an Avenger, get the weapons, jump out of the Avenger and fly back to the sub. Both aren't that hard or complicated, just some standard "get this stuff" missions.
Do not forget to buy supressors for your weapons, they're only $5k
2.7 Armor
For the 3 optional preps, you only need to do the armor, as the other 2 are only beneficial for going loud, which we won't do.
Again, pretty simple stuff, fly to a warehouse, blow up stuff, blow up more stuff inside the warehouse, blow up a boat, done. The Sparrow is absolutely your best friend for these kind of missions, just beware that is lacks any sort of armor, so when taking off you may get shot a bit too much at times.

3. Finale

Right, finale ,big money. Here's how the planning screen should look
Haven't tested other times of day, but night is the obvious choice for stealth
WHen the mission starts, you'll be instantly thrown underwater, right next to the compound. Just dive to the sewage tunnel, cuzt the grate and boom, you're in.
Inside, try to deal with all the guards before going upstairs to the office elevator. Standard stealth rules apply, kill guards outside of camera view, kill facing guards in quick succession with well placed headshots (not headshotting can cause the alarm to go off ~3s after bodyshotting them to death). Chances are, you will fail the first couple of tries until you get a feel for it. Here's the path I use:
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Looks complicated, but you'll get used to it
When reaching the vault room, you cutting torch can make quick work of the lock, then grab the main loot and get out via the exit to the right of the main vault, turn right again and you're basically next to the compound gate. Just confirm that route and you're out.
Once you're out, there will be 4 guards to deal with, not a huge issue, kill them and move on. There are bikes by the checkpoint, grab one and leave.
Once you are outside the compound, a heli will be sent to search you. Have a look at what direction it flies, it will always fly straight until reaching the end of the island. Evade him once and you're good for 5-10 minutes, plenty of time to leave.
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Path outside the compound, at green circle, evade helicopter
Drive to the docks, careful of the guards that only appear on the map once you're close to them, luckily at this point you're free to kill anyone you meet, so blast away. Grab the 2 warehouses worth of secondary loot, kill the guards by the docks and leave, even if you get spotted now, just make a dash for the open sea and get as far away from the island as possible until the mission finishes and you're done, $1,3m reward.
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And that's it, pretty simple heist, finale is made super easy by the sewage tunnel and the prep missions are already easy as piss

PRESS START<
Hey everyone since the update in GTA this newest heist has been the most profitable and easiest way to make money. So I wanted to create a guide to help others master this heist, and to help those who are struggling with it.
Note: This guide is for new players, first timers, and anyone who is struggling to complete this heist. Please use this as reference to deepen your understanding of the heist. If you have a better strat, more power to you. This however is my strat, criticism is welcome.
So to begin, you will have to buy the Kosatka (submarine), which is located on warstock for 2.2mil. It also has upgrades you can buy but the most noteworthy upgrade is definitely the Sparrow upgrade (1.8mil) this upgrade will make traveling back and forth much easier since your sub is located in the sea.
Noteworthy things about sub:

• If you hover above your sub with a sparrow you can instantly enter it.
• You can get free snacks at the cafeteria
• You can fast travel; if you never completed the heist its 10k, after completion its 2k
• Your toreador vehicle can enter through the bottom
• You can call dingy if you can not afford the sparrow

After you get the sub you’ll be introduced to characters and will have to go to LSIA, where you will travel to Cayo Perico, after you arrive everything henceforth is pretty straightforward. After you escape the party you will have to enter the main island through the checkpoint ( Google Boom Gate), PLEASE DO NOT SWIM AROUND THE ISLAND. You will waste so much time doing so, just run through the gated door next to the checkpoint and avoid entering enemy cones, watch for vehicles and watchtower cones. The biggest things to scope out are the infiltration points and exfil points; the airport strip is already marked, the biggest point to scope out after you hack the cameras is the drainage tunnel. This will require swimming, the drainage tunnel is located on the coast of El Rubio’s compound you can dive and find it, Pavel will give you a vocal cue when you find it. When you are looking through cameras after hacking make sure to cycle through every camera, turning to find secondary points, stop until you get back to the Panther Cage. Don’t bother scoping anything else like bolt cutter’s or grappling hooks, because you will not need them. I added a map of Cayo Perico to show where everything is, please note that there are many ways to do this heist this is just my way of doing so. After you found the drainage tunnel and finished your objective, get caught and make your way to the airport strip to leave. Also note there are different Primary targets the first time will always be the files the second will vary, look in the tips for scoping out to see the rankings.
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Credit to Sportskeeda
Tips for Scoping out

• On your second time doing the heist you will start at the air strip. There are 2 dirt bikes located at the strip one by the entrance to the strip and one by the solar panels next to the power station. You can take the bikes and drive up and over the checkpoint to get to the communications tower faster. At the checkpoint to the left there's a little stone wall in front of the guards tower. You can drive the bike up the ledge and get over it, for a quicker way you can also drive the bike up the ledge a little bit in front of the wall to also get over.
• If you solo, scope out any important secondary point. There's a secondary point in the airstrip hangar, at the entrance of the hangar look right to see the box you can climb, use this to get to the second floor to get the secondary point. (To clarify check the targets spawns and only mark coke and weed; do not mark weed at the strip and north dock only coke, mark weed at the main dock)
• When you are heading to the communications tower to hack, pay attention to the guard, if there is a guard, the box is located up the tower, if there is no guard it's on ground level.
• You can kill yourself or get caught to go back to the airstrip.
• You can also poison the guards water supply to weaken them but unless you're going aggressive don’t bother.
• There are boats out in water you can steal but I would only do this to scope out the drainage tunnel the first time.
• You only need to scope infiltration points and exfils points once, secondary targets and tools must be scoped out every time.
• Secondary targets and tools are RNG based so if you're looking for tool and it’s not there it’s because of RNG
• Secondary Targets Rank: Gold>Cocaine>Paintings>Weed>Cash
• These also will fill your bag different
• Gold=66% Cocaine=50% Paintings=50% Weed=37.5% Cash=25%
• The price for secondary targets are RNG based but Gold, cocaine, and Paintings have the most value
• Secondary Targets Values are RNG based.
• Gold=332k, Cocaine=220k, Paintings=189k, Weed=147k, Cash=80k-90kCredit goes to u/FMT_WL1
• Primary Targets Ranked: Panther Statue 1.9M>Pink Diamond 1.4M> Bearer Bonds 1.1M> Ruby necklace 1M> Tequila 900k

Preps
In order to start the heist you must do preps, for this heist you can do however many you want but for this guide you will only need to do 5. Keep your sub in Los Santos until the fifth prep mission, if you decide to do the longfin prep you can keep your sub at Los Santos.
Prep 1/ The Cutting Torch:
This prep mission is pretty straightforward, head to the construction site and land close enough. Before heading in, try to locate the yellow hard hat and put it on, this will make the enemy non-hostile, which makes for an easy mission. Your job is to locate the torch in a tool box. You can find it by looking in the box, it's a blue torch, search the box and head back to your sub. Also when searching for the box try to avoid staying in the enemy cones for too long and bumping into workers because this will make the enemies hostile if you do these.
Prep 2/ Safe Code or Plasma Cutter
There are two missions. The mission will vary on your primary, if you have the bearer bonds it’s the safe code, anything else it’s the Plasma Torch.
Safe Code Mission: Head to the casino at the entrance, after entering turn left and enter the elevator (if you have a penthouse you can go up without entering the parking garage). You will have to find a car in the parking garage. It's a yellow cheap car, it never changes. After finding it you will get the card which will allow you to head up into the penthouses, after getting up there search for two guards and head shot with a suppressed weapon. If done right you will calmly walk into the apartment, you can then search the penthouse for the target, he will never change. It's a guy with a cowboy hat, kill him and leave the penthouse, you will have to fight your way out. If you slam into the entrance of the penthouse you will have to fight your way in. After getting the code get back to your sub.
Plasma Cutter Mission: This is pretty straightforward, for ease take your oppressor instead of your Sparrow for higher mobility. You will have to head to the office to get the plasma cutter, but it’s not there. Pavel will instruct you to find the board and take a picture of it, the board is easy to find. Afterwards he will locate them and ping it on your map, they usually always spawn near Vinewood hills or the beach. Take them out with your oppressor missiles and fly over the bag and leave cause they will spawn two cars to shoot you.
Prep 3/ Fingerprint Cloner: This mission is simple, you will have to head to a location on your map, outside are two cameras, ignore them and walk into the garage, after entering take cover behind the box forward and blind shot everyone with your shotgun. After the enemies are dead hack the laptop in the back and head to the archives. Outside the archives are cameras, shoot them and go inside. Pavel will tell you that you're looking for a small card, it always spawns in the back in the desk square, grab it and head back.
Prep 4/ Weapon Load out: Always buy the suppressors, as for which load out I suggest the Conspirator due to the sticky bombs (there is a bug where you will get suppressors without buying them, just in case purchase it to be safe). There are two possible missions you can be given. One is in Los Santos in an office, for the other you will have to follow a Valkyrie up North.
Weapons Possible Mission 1: Pavel will send you to an office in Los Santos you can either go through the ground entrance or the roof, I suggest the roof entrance but no matter what you will have to fight inside. Once inside clear the office and head to the back to find the gun safe, it’s always located left of the desk on the wall, hack the laptop on the desk and open the safe. Grab the weapons and leave. If you enter on the roof you can fly back but two chopper’s will spawn, shoot their gunman on the sides and hellies will be useless. Another suggestion is to leave immediately, and snack up to restore health. On ground level the hellies will still spawn again shoot the gunman and head back to the sub.
Weapons Possible Mission 2: You will have to head to Elysian Island to find the Valkyrie you do not need to stay close to it. You can predict it’s direction and head North to clear the camp on foot, also avoid destroying the Avenger and the Valkyrie. Do not destroy the Valkyrie until it becomes a target on your mini map or you will fail the prep. After clearing the camp head into the Avenger and kill the enemies, afterwards parachute out and leave before more Merrywheather show up.
Prep 5/ Kosatka: ( You can also do the Longfin, but I prefer Kosatka as an approach vehicle.)
This is a simple mission, after starting it head into your sub driver seat and fast travel to the nearest location near the ping. After you arrive dive your sub over to the location, once you get near get on your periscope and missile the boats and the helli. You can sink your sub and engage auto-pilot under water giving you better access to the enemies sub. Try to avoid beaching your sub on shallow water and put it in the middle of the yellow circle. Leave the driver seat and exit your sub, dive into the water and look for the other sub with a yellow marker on top. After entering the enemies sub you must locate the jammer. You have two paths, one on the right, this is usually where it spawns, take the ladder down and watch your corners cause enemies are brutal in this mission. After entering the engine room look for a black box with a blue screen at the bottom of the stairs if it's not there head back the way you came. Take the left path and make your way to the control room WATCH THOSE CORNERS. If it's not there head to the back of the control room and take the stairs down, follow the path it will lead you into the torpedo room, that another spawn. Leave and head back to your sub.
Prep 5/ Longfin
This mission is located in Los Santos basically you can take a phantom (Semi-truck) to the police station to pick up a boat of which you can use as an approach for the heist. This mission is simple: you basically go and pick up a phantom, afterwards you drive to impound to pick up the longfin. You will be met with enemies. The one I did was the cop impound, you can enter with your phantom and drive out. It's best to clear the area, and let the cops kill you for an easier delivery (you can't call Lester). You can use your own Phantom wedge to clear vehicles out of the way.
(during the heist you can use this get loot before you enter the drainage tunnel , this can be quicker way if your loot is out the way)
This includes the scope out and the preps
This includes the scope out and the preps
Tips For Preps

• The biggest tip is the Sparrow, this will make prepping a joke, the only time you won’t need it is during the plasma cutter and Kosatka missions, but that's due to mobility.
• You can see the cutting torch it’s blue
• You can blow up the Valkyrie and end the mission to get the office mission to save time, I highly suggest this ( I do this mostly because you have to follow the helli up North and wait for it to land.)
• The preps are the same, they never change
• Save the Kosatka heist for last so you can do all 4 preps in Los Santos

The Heist
Time to Start the Heist. Go to screen and tab to Finale and shift over to continue to start the mission. Once you get to the selection process pick your options. It should be Kosatka or Longfin, Drainage, Drainage, Main docks or Kotsatka, and Day Time (there's very little difference between day or night). If you're playing with others you must hurry through the selection screen because if you take too long the cuts will reset due to a bug.
Squad Run
When you begin the mission you will have to make your way to the drainage tunnel, if you chose the Kosatka you will have to swim to the tunnel, but if you chose the Longfin you will have to drive the boat to the tunnel. Once you arrive you will have to cut the bars at the gate, a suggestion to do this is to go in a circle three times and cut whatever remains. Afterwards swim through the tunnel and enter the compound.
Compound
Once you enter the compound you will have two directions to go, the left or the right. My way is to go to the left, up the stairs is a guard next to the storage staring out at the water, head shot him and make your way to the courtyard. If you followed my instructions the two guards at the pool will be to your left. In the courtyard there should be a guard coming, wait for him to stop and head shot him. After that, ready your shot at the two guards at the pool, choose your target. Since you're in a squad, ready your shot, as a suggestion one person can count down from three to one to shoot at the same time to eliminate any mistakes ( these two guards usually drop the gate keys). The next is to eliminate the juggernaut, the way to identify him is by his red cone and red skull icon. He can be killed by a single headshot, if you and your squad were quick with the guards at the pool he should be arriving, take him out. In front of the pool there are two separate guards, one will be in front of the office building to identify him, the camera is facing the pool, if you time it correctly he will be to the right of the camera making for an easy elimination. The other guard is North East of the front of the pool, or to the right of the guard you just killed. You can eliminate him if you want too, the reason I do so is because me and my mates can all access the storages without worry. Next are three guards at the office, to identify them they will have red cones. One of the guards will be moving North towards the main gate and then will move South towards the pool. You have two options, one is to wait for him to head North and take him out, or you can head shot him when he’s coming South. To achieve this there are stairs directly in front of the pool, if you take the stairs up to the right you now have enough elevation to see the guards head ( this is tricky to explain which is why I will also have a video example for visual clarification.) After taking the guard out you can head up the stairs into the office area, once up the stairs head to the right, for clarification the pool will be to the left and main gate to your right. Head down the corridor if you have done this correctly the guards back will be facing you, take him out. To your left are stairs that leads to the office, take them up, at this point the guard at the top will start to move. You have two options, one you can wait behind a corner and hit the guard or if you are quick enough the guard will stop for a brief moment, giving a chance for an easy headshot. At this point you can enter the office, where you can grab the second keycard, the first keycard is dropped by any guard you have killed ( it usually drops on the first kill, but this is RNG based). In the office there are three things you can do, one is you can hack the elevator which leads to the basement, ignore this hack. The other things are either a painting that can randomly spawn in the office, and a safe on the right wall in the back of the office. Open the safe to get anywhere between 50k to 100k, THIS DOES NOT TAKE SPACE. When you have everything, start to loot up and fill your bag by going to the storages located around the compound, to open the storages you will need the two keycards and two people. You and your squad mates will have to swipe your card at the same time to open the door, another suggestion is to use the three to one countdown to sync swipes. The South Storage will have a guard moving, the guard is located to the left of the two guards you killed at the pool, take him out and watch for the camera. After you are done, please make sure to save space for the basement storage, make your way to the basement gates, they are located beneath the office building to the left and right, it does not matter which gate you choose. Once you are in the basement you will be presented with a hack, it may look daunting but in fact it is rather simple, I suggest matching the top first and making your way down. Afterwards loot up and grab the Primary Target, it is really straightforward to do so. At this time Pavel will tell the players that more guards have arrived, if you have followed thus far, you do not have to worry. Exit the basement, and head North to the main gate there should two guards, one will be moving the other stationary. You can take the stationary guard, you can also take the guard moving but if you and your squad can make it to the gate without doing so, go ahead. The host will be prompted to select the escape route, select it and a cutscene will begin. After you will be located outside the compound.
Kill in this order
Outside The Compound
You and your squad will be outside, if you are satisfied with your loot head left to the coast, you can jump off the cliff into the water. Once in the water you can swim off the island ,just keep heading straight and eventually you will have escaped. You can also try to steal a boat; note that some have claimed that boats may not spawn but if you manage to grab a boat this can make getting to and from much quicker. If you are missing loot head forward and take the guard next to the bike out, one person will have to head left toward a guard near a helli take him out and plant four stickies on the chopper. At the same time the other members will turn right towards the checkpoint, there should be three guards two together and one separate, and a camera behind the two guards. Take the one separate out, then the two guards, and the camera. Around the checkpoint are three bikes plus the bike with the very first guard killed. One of the bikes is hidden to the left of the checkpoint booth the other is directly in front. Start making your way towards the main docks, turn right into the jungle the moment you leave the stopping checkpoint. Pay attention to the guard tower to your right and avoid his cone, at this time Pavel will tell the squad that El Rubio’s helli is on the move, activate the stickies and he will retreat away from the island. Once you are close enough to the docks go on foot, your objective is to loot and take the boat off the island. There are two secondary loot locations, one is a warehouse with a guard and camera outside, take them out and loot. The other is located to the right with two separate guards, please refer to Sportskeeda map to see the location. Take them out and loot. Afterwards there are 3-4 guards you have to take out at the docks, to leave without alerting the guard. Two guards standing next to the boat, and one or two stationary guards looking out at the water. After clearing the guards, grab the boat and escape Cayo Perico. Congrats you have now completed the heist.
Note: You can approach the compound in any way you choose, my way is a bit complicated but with practice you can clear the compound at the same time as other routes. Feel free to adjust the route in anyway, my route is just a reference to get an idea as to how to approach the compound.
Note: I do it the same exact way when I solo, but since I’m solo I can skip guards and head to my objective. For the Solo run I go for cocaine, you NOT have to do this. I do this to maximize my profit, and since I am competent in my abilities I can clear the mission without many mistakes.
Solo Run
The strat is the same except it will be harder to take out the two guards by the pool, the major difference is you can not open the storage's to get gold or loot, you might be lucky to get painting in the office but that's RNG. A good tip when taking on double guards is to find a good angle, after killing one the other will flinch, he will prop his head up giving you the shot. You can scope the rest of island to find the most profitable loot which is cocaine, if there is none then get weed and cash (by scoping out I’m referring to checking the spawns for coke, if there is none at North docks and the Air Strip I ignore them, I do not mark every item only Coke and any profitable items at Main Docks). After leaving the compound there will be a guard in front of you next to a bike, kill him. Turn left and head to the next guy next to a helli, kill him and plant four stickies on the heli, do not activate them yet. Go back the way you came, there will be three guards at a checkpoint two together, one standing away. Kill the one standing away and then prepare to kill the two guards, after their dead shoot the camera and jump over the stop rail. You will have to be quick because a car will drive towards the checkpoint so make sure to do all that quickly. You have two options: you can swim off the island and finish the heist, or you can head to Main Docks to fill your bag. If you chose the latter run North East into the jungle towards the guards tower, but far enough away so he can’t see you. On your way to Main Dock Pave El Rubio helli will show up on the map, wait for Pavels vocal cue when he tells you that Rubio is in his helli, and then activate your stickies, boom Rubio will retreat. Now you can make it to your objective in peace. You can loot at the Marijuana fields but you may have to take out three guard towers and a single camera, as well as two guards near the fields. I’ll leave this to your gut if you think you can make it to the warehouse without messing up please do so. If you want to head to North Dock and the Airstrip you either can swim there which will eat a lot of time or you can take the boat at the docks to get there faster. Trade off is that if you swim it will take up time, but if you take the boat you will have to clear out guards to safely remove the boat from the dock. If you are satisfied with anything you get then just clear the area with loot and swim or steal the boat. This is for the Airstrip if you do not plan on going here IGNORE this. The Airstrip is an easy place to navigate since a lot of the guards are far from each other so you can clear the airstrip easily. There are two loot spawns one at the hangar with one guard, and a warehouse with two separate guards. There's guard outside the hangar kill him, and go inside, if your loot is on the second floor, look for a forklift and pick up a box lift and it up then press the box against the back of the hangar below a blue tarp you can then climb the lift and the box to get access to the loot. The other airstrip loot spawn is an easy place to clear, one guard will be moving you can head shot him from the hangar, at the warehouse there’s a camera shoot it and inside the warehouse is a guard questioning his career choice, kill him. If you need to head to North Dock head there by bike or by foot, you can loot without killing any guard. After you're done just swim off the Island, or take the boat. Congrats, you have just completed the heist solo.
Note: I will be adding a second strat to clear the compound, the reason for this is because a Redditor provided the strat. I do not mind adding his strat, but I must remind everyone that you can tackle the heist in any way you feel comfortable with.
I missed that gate keys, so I killed more than I should have.
Solo Run Second Strat:
Essentially, it is the same as the other one, except for going left you go right. Your first target are the two guards at the pool. They should be to the right of you, find a good angle and head shot the first one, wait for the second guard to finish flinching and kill him. The juggernaut should be making his way towards you, wait for him to exit the camera’s view and kill him. If the gate key drops pick it up and kill the guard in front of the pool he should be past the camera. Take out the camera and wait for the moving red cone guard to turn his direction North, once he turns around go up the stairs and kill him. Move towards the second red cone guard his back should be facing you, hit him and ascend the stairs. The last guard on top should be moving. You can either wait behind the corner and hit him or speed around the corner to head shot him, it’s up to you. Loot the office safe and make your way to the basement. Finally, use the gate keys to open the basement, hack and grab the primary target. Afterwards head up towards the main gate, a new guard will spawn, you can wait for the moving guard to move out of range, and kill the stationary guard. From there you can run to the gate and exit the compound.
I had brain fart at the hacking lmao
Heist Tips

• You can swim off the island from any direction
• You can steal boats for faster escape but that's up you
• You can sticky El Rubio’s helli for to get him to retreat
• In the compound you can jump ledges after clearing the enemies
• For double guards, get a good angle after you head shot one guy the other will flinch, you can get the shot slightly after, or you can risk shooting him until he’s dead.
• Guards do not react to dead bodies, in day time their visibility is the same as night, an Isolated guard can’t alert if everyone is dead. You can run, guards will only react if you're close, if you miss a shot and it gets near a guard or makes noise this will alert.
• You can jump into the ocean to die quickly if you alert inside the compound
• If you find a key you can open the desk to get a golden gun
• If your underwater and a patrol boats cone is on you, they can’t see you
• Cones can be obstructed by objects
• ? Civilians may be able to alert guard?
• Solo is more profitable than playing with friends due to not sharing a cut
• If you don’t have to kill don’t, less interaction is good
• Being stealthy is the best way, if you alert restart
• You can aim in and hold the sprint button to walk faster
• To activate hard mode, you have to start the heist when it becomes available
• Try to avoid killing guards near the camera cones, the reason being is because this can alert the guards if the camera sees the dead body. Ironically, guards do not alert they seem one.

Game Over>
That's it ladies and gentleman, I hope this guide has helped anyone. I’m aware I’ve definitely went too in depth in this guide but I enjoy making it, Happy Grinding -Leaus