: I fill the gaps with flour/epoxy first. Yes, it might discolor the hull, but
: no more than doing a seal coat first. ....

To each his own, but I have to strongly disagree here. I asked about this very same problem awhile back and received what was in hindsight an obvious solution.

My Problem - on an earlier boat I had filled some gaps with thickened epoxy before applying a seal coat. The thickened epoxy mixture soaks into the wood pores at a different rate than a uniform, viscous seal coat. The result was a splotchy looking finish on my first boat (that EVERYBODY notices!).

Somebody on this board (bless 'em) told me to seal coat first, then backfill. Well, Duhhh!

My Advice - Wet the boat out completely with the seal coat first, then backfill. The thickened epoxy won't be able to soak into and discolor the wood surrounding the filled gap. I think I put the seal coat on, then proceeded to backfill before the seal coat even set up. Scrape off excess filler before it sets, and you'll have very little sanding to do - certainly not enough to force you to sand through the seal coat. It worked beautifully on my second boat.

Whatever method you use, good luck, and just ignore the 2%'ers!