Keep in mind, you can spray enamel over lacquer, but you CAN'T spray lacquer over enamel.

When you sand, it is wet, not dry. Otherwise you clog/fill up the paper real fast. You "almost" can't use too much water.
The exception is when the floor is so wet, the "boss" starts soaking water up through holes in his work shoes so his feet get damp, then, well, it gets ugly......LOL.....

Sanding gelcoat is sorta like polishing granite with wet toilet paper, lots of work with minimal progress, trust me, I know. Yes, you can go coarse, but the coarser you go, the faster you can go too far and have to lay more gelcoat down.....sigh.

PS, IIRC, spray enamel using "titanium dioxide" (or was it trioxide?) was a close cheap rattlecan for some gelcoats. Also look up "automotive touchup" online, they can provides gallons down to rattle cans of car paint colors.