I've been slow with updates. The trailer made it to SEMA, via San Dunes at Dumont. It's tough to tell how smooth the ride is on dirt roads, but I didn't even know the trailer was there on the highway. I had to slap things together, trying to get the trailer ready for the trip. I'll be doing some finish work, before I post any more pictures.
I managed to source some good adhesive backed neoprene foam tape. With the lid hinges I used, I needed 1/4" and 5/8" foam tape to seal between the lid and the box. Both are 1" wide and I'm very happy with how it worked out. The supplier required a minimum purchase order. As a result, I have a bunch of 1/4" tape left over. If you're looking for 1/4" thick X 1" wide X 60' neoprene tape, then send me a PM. I can sell them for $20 per roll (CHEAP).