Are you planning on having any rear drawers or putting the mtbs on a slide?
Yes the mtb slide is done. I'll be taking out the seatpost/saddles so that I get a few more inches of headroom. I've also put up new wall paneling over the exiting utility ply. The bed build is delayed until I'm back from EAA Oshkosh in a couple weeks.
I used a polyurethane caulking/adhesive by “Sikaflex” - on my high top and it bonds well to the paint if it is sanded first and cleaned off before applying the caulking. It comes in basic colors like white, grey, black, tan, etc...
I self installed my 30" camper top. At the recommendation of Fiberine, I used silicone between the flange and the roof, and (my own decision) used loctite pl marine polyurethane sealant around the edge.
After 20k miles of rather abusive travel around South America, the top remains well sealed.