I would love to see this discussion move over to the boat builder’s thread:
The way that Chesapeake Light Craft does it is they sandwich two plywood bulkheads with a layer of cardboard in between. When the boat is built, you then saw the boat in half and the saw follows the path of least resistance through the cardboard. A little cleanup and some neoprene and you’re good to go. Oh, the bolts were already epoxied into the plywood prior to construction.