i think the truck should be included in the theory of how he survived but i really don't think he landed in it. as i've said, no human could survive a fall into a truck no matter what it was filled with (unless it was a huge stunt crash mat which we could see was not in the truck) and from the way he was falling he a) obviously hadn't jumped far out enough to hit the truck; he was always going to hit the pavement/a tree and b) i'm pretty sure it wasn't a corpse falling because corpses don't flap their arms like that x)