Now is the time to fill the laps and the keel seam the rest of the way with a epoxy mixture that has been thickened with a lightweight filler. You want a mixture that will flow into the seam without leaving any air bubbles, but still be thick enough to hold it's shape when radiused with a Popsicle stick. Mix it a little thin at first and add filler until the consistency is right. Using a cut off Popsicle stick as a putty knife, fill in any rivet holes that were not completely filled by the unthickened epoxy. Pop any air bubbles before the epoxy starts to cure
Sand the plank ends to give the stem a fair curve, and round them over so that the fiberglass will wrap around the stems without trapping air bubbles. If needed, fair-in the lap gains with a sandable epoxy mixture for a distance of 4" or so from the ends so that the fiberglass tape on the stems will lay flat.