AJ, I'm in the process of removing all of the carpeting/vinyl headliners in my Sunstream 40 and have used textured frp panels
(available at Home Depot for under $50.00 a sheet). Looks terrific and is a permanent fix. If there are significant compound curves you may have to epoxy
in some wood pieces underneath, but otherwise it is fairly straight forward: make templates out of bristol board, cut with a saber/jib saw, sand the edges and use either the proprietary frp adhesive
resin. Caulk edges/seams with a good quality white bathroom silicone.