I have a sea king that needs the bench seats replaced. I have some plywood that the prior owner cut to exact size but never got around to finishing them. The plywood has kind of twisted so that it doesn't lay even close to being flat. I can manipulate it by hand to slide into the front and back aluminum rails that holds the seat in place. If I fiberglass the plywood will it still flex enough for me to be able to manipulate it into place and get it installed or will it lose it's flexibility?