thanks guys I was thinking the nice stained wood kit with painted steel or stainless runners would dress up the rear. I'll find a buddy with a 1/2 ton and make a quick paper template to see how close they are. I'm a long way from this being at the top of the "to do" lists.
If you go this way, take a router and mill away half the thickness of the plywood sheet, about an inch from the center on each half of the floor, and make an overlapping joint. Some wood glue along the whole seem and clamped well will keep the water from seeping through, and it'll eliminate a weak spot in the center of the floor.
-Brad
