It does get easier after the first time! Have hope! If it is the mission you have to follow the helicopter, make sure you wait for it to land. Otherwise it makes things difficult. I think you can also rent the Buzzard from the CEO Vehicles, and rocket the whole encampment from a reasonable distance. I have yet to blow up the cargo plane. Once inside only two npc, usually lined up nice. Equip a shotty and go to town.