I'd use gravel guard. It's flexible, and retains texture. Tough as hell too. In fact, my GS interior is covered in it.
To use it, sand and degrease the panels. Then spray it on. Let it cure for a day before it goes in the car at least.
To use it, sand and degrease the panels. Then spray it on. Let it cure for a day before it goes in the car at least.