I know Big Blue installed a really really bright light on a door switch in his 87 Montero SS. He pulled a door switch from the front door of a junk yard 88 SWB. He installed that switch in the Montero's rear door jamb. Then he placed a couple of aftermarket lights with extra bright bulbs in the above the cargo area.

Every time he opened the door the light would come on. It was a nice system and a small detail that other vehicles have that our older rigs don't. At some point, I plan on performing this upgrade at some point and writing up a nice little forum post and procedure.