Fleetwood touted their Vacubond construction detail for walls. The walls are a sandwich of fiberglass, metal cage with foam between, and a wood paneling. The whole is laid on a vacuum table and glued together, then installed on the chassis.
If there is any way to restore the walls by overlaying, painting, or applying a covering, I would choose that. I think the interior panel removal will be difficult. Installing replacement paneling will also have it's quirks.
You could look through my build thread in my signature line, "The Cowboy/Hilton" to get an idea of some of those projects you've planned.