Oh let's see, first thing I would suggest is to run. Second, I wouldn't accept anything but cash from this customer and preferably up front.
Seriously, you don't know how the lights operated before the fire, right? This could have been going on to begin with, no? I seem to remember there being a couple of different door ajar switches for 1 year model that were not interchangeable. This caused many problems at one time and gave us and the parts department fits. If this guy is willing to burn down his truck to get out of it, how much is he willing to pay at dealer rate to fix interior lights?
What happened to the good old fashioned parking your vehicle in a bad part of town with the windows down and catching a taxi out of there?