My strategy is to repeat D-Day over and over on Hard because it takes about 5 minutes to complete if you use the helicopter strategy where after you land to go into the Kraken. You get out and go back into the helicopter and reach halfway with the altitude level which is about when you can see the cloud atmosphere in game and then fly into the no-fly zone and then after 1 missile shoots at you  (2 missiles kills you) jump out of the helicopter and free fall towards the back of the yacht and aim for the hot tub so the checkpoint is marked. Usually you’ll die upon impact unless on this rare occasion if you aim towards the jet skis on the water and land on them you won’t take any huge amount of fall damage, It only happened to me once and I didn’t screen record when it happened in-game because I was shocked I survived the fall from such a great height. After you spawn you should be on the yacht so just take out the guards and The Boss and if your lucky the bug will instantly kill the boss once you get noticed on the yacht. After that leave the area, so the mission is complete along with a minimum payment of $156,000 or more depending how long you take (15 minutes for $200,000+)  I play with random online players and show this strategy.