[mswartz]

Mark and Bob,
Thanks for the comments.

I already have the stainless sheet since I got a great deal from a vendor I know. It was less expensive than the 5052 I was originally looking to get.

Good idea on overlap painting.

I agree on the concern over damp fiberglas, and am leaning toward the "reflectix" type sandwich insulation, stood off from the plywood by 1-in square stock to allow the air space.

Since bubble-foil primarily works by reflecting radiation, and since the floor is not the primary heat sink/source of the trailer, and since I don't want to trap transpiration moisture between the foil and the floor, I'm going to leave some- as yet undetermined- open gap on the standoff material perimeter within each segment of the frame which I hope will allow some reasonable ventilation without excessive circulation. Any thoughts?