Yes, save the roof and siding edge trim. That is usually made of aluminum so all it needs is a cleanup and can be reinstalled. There was probably a plastic screw cover that snapped into the trim piece. It is available in rolls in different colors.
If you can see visible water`damage inside, I'd suggest to pull the damaged stuff out to inspect the extent/lack of frame damage. You'll need a good frame structure to reattach the roof edge trim and to support the roof so it remains leak free after your sealing efforts.
Any frame damage may seem daunting to repair but it's all straightforward. If you can build a doghouse, you can repair a TT. Good luck with the Prowler, it certainly looks like a worthy candidate for some TLC.
Edit: I painted the Hilton roof with white elastomeric roof paint, not the most durable stuff, but it did lower the inside temps considerably.