Wow you're hard at it.
I completely understand the motivation-sapping nature of finish sanding hardened fiberglass resin.
My
partial Kammback project sapped many, many hours for finish work. Then my paint job sucked. To add insult, now several years on, the finish has bubbled, cracked and flaked off in several spots for a variety of reasons (from poor surface prep, to water wicking / mild delamination).
I really envy guys who have the skill and time to make a pro job, but as long as it works... halfassery is my new approach (in the looks department)!