I replaced the rear side trim panels today. Mine were scratched and gouged from the previous owner. When pulling down the roof headliner, I found the compass module. Underneath the rear floor (part where the floor latches attach) was another sensor and of course there were tons of black boxes behind the side panel itself.
I also found the emergency gas tank release. How on earth are you ever supposed to actually reach it?? I have a large module in the way. (Sat radio, IIRC) I guess maybe you could take the tire iron and use it to pull it. I haven't tried that, however.
Also, when removing the chrome trim plate that surrounds the tailgate latch, I found a large amount of debris there. I guess the spring loaded latch cover is only cosmetic and not very functional. :- /