I did a double bulkhead at the bow side of the centre thwart. i made 2 identical bulkheads and temporarily fixed them together with softwood spacer strips that were the thickness of my favourite handsaw. I also drilled the holes for the joining bolts. I then made the boat as per instructions except that i epoxied inside seams first and then cut the boat in half.
i then did the outside seams.
Actually i made bottom and sides from 4 mm ply as i wanted lightweight, then added single layer of 200 gm/m2 cloth over the bottom and 50 mm up the sides for strength and abrasion resistance.