I have a feeling i will get through doing it that way but it's like a survival mission on steroids when you're alone.
The best I got to do so far was find a barn near the south end where I can park my car in away from the missiles and hold off as many npcs from the doorway as possible pulling out my minigun anytime one the the helicopters are within aim from there. Not only do we have to deal with all the aimbot guards all over the place, but also 2 types of helicopters that shoot missiles constantly. Never have I looked at my armored Karuma to be so useless against an npc fight situation like this one. Even if I had another player in there with me, this mission seems very hard to pass. The mission where you have to go take out that ems like the finale. The ones from the Casino management office that we had to do with 2 or more people before the latest update.
I finally got around to doing the Casino missions with Agatha now that we can do them solo.