I replaced the metal above the inner fender with 1/16" aluminum... Wish I'd used steel... But that was back around 1998, so I haven't any complaints. It's held on with self tapping screws. Some day I'll weld in steel.
The black in the corners is conveyor belt. I added an aluminum stay to keep it from flapping... Won't rust or dent.
I custom made the rear bench back around 1992. It's getting a little beat up so I'm planning to replace it with a Caravan seat which has adjustable sliders. It will be removable rather than just tipping forward (which is all the current one does easily). The seat will seat 2-3 adults in relative comfort, but the roof is a little low for me at 6'4".