I’ve heard of some using pickup truck bed liner in places like under fenders and it can protect the fiberglass from stones.
Sounds like a plan, should be pretty tough. Been out today but did a bit more this evening - front end cleared so inside now. I'd forgotten what an emotional rollercoaster restoration is. Getting the passenger seat out was the usual mix - sill side nuts just turning underneath, and couldn't see the bolt heads, but then realised the seat runners had disintegrated and not holding it. Front inside came off - nyloc nut!
Rear inside just twisted though, and had to grind it off. Seat frame looks of, but now need a set of runners.
More daft questions - whilst lying on the floor to get at the seat fixings, I noticed a hole below the passenger door - no idea what it's doing there or why anyone made it - can't see what it would access. And there was a plaque riveted to the n/s sill at some stage, any ideas what was there?