Just purchased a new Coachmen Freedom Express 238BHS and had to cut an access hole (flap) in the underbelly to repair a leaking shower drain trap. I tried sealing it back up with regular Gorilla tape and the Gorilla tape that looks like Eternabond but they ended up failing. My plan is to use 1/4" plywood around the edges of the access hole with screws and washers to fasten it back up, but I still want to seal the seams with tape. This underbelly material seems to be a bit different than the normal coroplast though. It looks like the normal corrugated plastic, but has a "fabric" finish to it which I think interferes with the tape. Does anyone have a suggestion as to how to seal this back up?