Has anyone ever cut out a section of their trailer's under belly to gain access to plumbing, etc.? If so, how did you reattach it? The covering on my trailer is a sheet of flexible rubber.
remove the whole panel do your repair put it back in place no more worry's or you can cut it out and glue or screw the piece back in by glue a piece to the inside an then glue or screw your panel back on to it them run caulking around the seam to seal it up