Randy - you could build a scaffolding framework, using 2 by lumber, from the floor extending through the openings, use some jacks (3 or 4) to raise it a bit at a time. I did the sedan I originally started with that way - I did have the doors off to reduce the weight. My arrangement was not for the faint of heart, but I was able to get the body on and off my rolling chassis a few times.

Mike - glad to hear that you too are progressing