i was there when mel was building the boat sides for ali's TJ , very cool and thought out. they are heavy as hell and it took em along time to get em worked out. lots of work to get those put on
the big issue with what you want going from body to frame is how much the body moves on the chassis. if you want to just get it close your actually loosing ground clearence.
alot of XJ guys do it but they are unibody