Grummy, I'm going back and forth on whether to insulate the bottom or not. I read this posting that says a waste of time, and another that says it helps. We are not winter campers per say. Though the heat off the asphalt pads we park on sometimes can get awfully hot.
To insulate the bottom, would be better when the plywood is out of the trailer for sure.
I know the crunch finding building material maybe hitting everyone, but damn, it's really hitting hard around where we live.
No baltic birch plywood available, cabinet shops where I use to get it, have none. Lauan ply is not available. Even the foam insulation is a hit and miss.
One place yesterday had 87 sheets of 1" foam, went to another site to check prices, they didn't have any. Went back to place the order at the other place. 87 sheets were unavailable.
I may have to start collecting boxes from liqueur stores and using cardboard to insulate this trailer.