When I banged on the sides hard with my fist, it was my hand that got hurt. Very solid indeed. There is Coremat in the sides, but when the builder takes the time to thoroughly saturate the material, this stuff gets very hard. And the deck is attached with screws into an aluminum backing plate. Due to the design, it's not possible to glass the deck on.
Deck join as seen from inside.
The framing system is something to behold. I was shown drawings of it since you can't really see the whole framing system. Larry didn't want me to publish the drawing because he considers this proprietary. If the competition wants to copy his methods, they'll just have to buy one of his boats and cut it apart. There is storage space galore on this boat, most of it in under-hatch bins.