We've been considering putting some kind of rubberized "rhino liner" on the fiberglass bottom of our amerigo
...so many rock holes and other holes there, so much patching...whatever coating was on it originally is all messed up. A product called "DURABAK" has a really nice website with tips and examples, photos and they'll send you free samples of their lovely rubberized paint
(smooth and textured)...I finally ordered a chip of ALL the colors, which they sent for free very politely. It's LIKE the rino coating but the colors are very nice.
It's kind of goopy, and once opened, won't store well if you don't use it all. It's pricey to have shipped--BUT you can get it in white and some colors, you can blend the colors, so whatever color scheme you're going for, you might be able to match or come close.
NOT sure we're going to, but if it were stlll off the frame AND accessible, I think I'd go for it. The rocks really do a number under there, and we're hoping not to have to fill 59 holes again--they ought to "mostly" bounce off this rubbery coating.
(He may still crawl under and do it...we'll see.)