Having built a few of Dave and Scott’s designs, I couldn’t agree more that the full length interlocking holey braces nested to just gently kiss the drivers’ magnet assembly are a pain in the monty -a few vertically oriented rib braces, strategically placed so as to not divide the opposing sides evenly would be much simpler, and still provide a good measure of bracing to reduce panel resonances. I’d still highly recommend using cleats for the full perimeter of the rear panel to allow for its easy removable to adjust levels and even distribution of fibrous damping fill, with at least one or two of those ribs connecting the front to the back. Seal with self adhesive closed cell weatherstripping tape.