Sounds like you need something stealthy (not a theft magnet), with most of its value hidden away in the oily bits. That could mean something that looks ratty (a Porsche "rat rod?"), or it could mean something that looks nice but doesn't attract too much attention, so you have some choices to make.
Either way, I think it's a really interesting problem, and a thread I look forward to following.
Maybe this (w/Porsche power, or course!):
