Wow, that rear suspension on Cambells rig looks just like "Tiny's" set-up.
Okay, rear engine cool, but what about something more like a mid-engine design? Could you put something like a small inline four cylinder alongside the driver? Besides heat, and possibly width what other issues would you have with a mid-engine?
What about something like a sideways mounted import motor? Hook that up a beefed import tranny something maybe out of a Civic SI? Put the motor and tranny right behind the driver, and that would stick the major wieght right in the center.