Damn, that's a good idea flipping the toons around to put the good side out. Mine are really bad outside, but perfect inside too. Might have to do that too.
What I do is leave one corner open with nothing on it at all to allow it to drain off the water. no plastic or carpet. and when installed I make it the lowest corner.
Got the trailer sanded and painted, bunks replaced, and pontoon framework reassembled. Working on the flooring right now. I'm applying a couple of coats of oil based porch paint to the underside before installing. I'll paint the top side once they are on the boat, hopefully this weekend. Plan on covering that with some non slip coating of some sort. Should have some more pics this weekend. Thanks everyone for the encouragement.