Unless your caravan is quite old, as others have said, the doors won't be wood; the door frames will be DMF covered with a plastic veneer. You won't see the join. The ends of the film are in the slot where the panel is inset. Don't use any abrasive on the surface. You'll quickly remove the surface of the film, leaving a dirty brown surface behind. The panels are made likewise. A thin sheet of ply covered with plastic film.