Morris Minor Owners Club

Does anyone have any experience, tips, suggestions about trimming out the rear cab of a pickup? I’ve been thinking of covering the rear panel with one inch foam and covering that with vinyl. I’m looking for something to trim out the rear window. The PO had covered everything with a sheet of pasteboard and glued black vinyl to that. They finished the window opening with piping and secured everything with chrome screws and finishing washers. This left a number of holes in the raised boss around the window which I would like to cover up.
I think metal would be very difficult, beyond my hammering skills. Plastic, rubber, fender welting? Anybody been there, done that, have the tee shirt?
Bill B