I ended up applying wood filler and sanding at this point. First, I was worried that the rough handling during sanding might damage the transom pieces if I attached them first. And second, I was just impatient to get the nice, smooth hull that I hoped for.
Using 1/16″ x 1/16″ strips, I have filled in part of the counter. It’s clear that I’ll need some filler to patch the gap between the hull planks and the counter planks.
And more planking… This is only my second time planking a hull, and it shows.