I managed to get the trunk floor welded in without warping it. I had to cover it with a coat of spray bomb enamel. The weather is changing and bare metal doesn't last long around here. I'll have the rear body buck in for probably a couple months so I wouldn't be able to paint it later if it started rusting.
When the time comes to put the epoxy primer on the body, I can just wipe this junk paint off with some lacquer thinner and a rag.
Tomorrow I'll get the backbone of the buck back in the car and continue plotting out the station locations and shapes.