Joe, on those spots where you can see very little fiberglass on the inside of that gel coat, you may want to consider beefing those areas up with either fiberglass or kitty-hair (fiberglass laden body filler) before you sand away the gel coat. I don’t know of any stripper that removes gel coat without also attacking the resin in the fiberglass…
Fiberglass shops are inherently dirty places. About the only part of a fiberglassing operation that’s even remotely clean, is the mold cleaning, waxing and gel coat process..