There's also this to consider: If Fosset survived the crash, he might've tried to walk out of the area. Pilots are taught that the best way to survive is to stay with the wreckage (it's normally easier to see a plane wreckage than an individual). However, if he knew his plane was in an area where it'd be difficult to locate from the air or if he believed his chances were better, he might've tried to walk out.

Also, whether he did or didn't survive the crash, it's likely his body was eaten by animals. Animals sometimes carry things quite a distance from where the body died.