OK, I have the wood for the inner cabinet all cut, the woofer holes cut, and dry fitted one of the cabinets.
The next step is to buy the kits. Once I have a driver I can finish drilling the pilot holes and start assembly.
My additions to the standard design will be to add a second layer of 3/4" MDF to the top, bottom and sides. These pieces will extend 3/4" past the front & back, allowing for a frame to hold a grill cloth.
The inner cabinet will be screwed and glued. I am thinking of using the 45 degree pieces I cut off the baffles to brace where the baffles meet the top & bottom if the drivers will allow it.