We've had two Haulmark enclosed trailers (16' & 20'), a custom built 24' stacker, and now a Solares 20' enclosed. I think most are built about the same. I prefer smooth sides, not screwed. Looks much sleeker.
Currently outfitting the new Solares with 110v lighting & power, electric tongue jack, workbench, tire rack, and a bunch of Pit Pal stuff. I had it built with tandem 5200# axles because almost all trailers around this size are made with 3500# axles. That's too light considering the empty trailer will weigh around 3300#. I vastly prefer excess capacity versus being close to or overweight.
I also had it built with hidden dovetail, two roof vents, three 12v lights and an RV style door. We'll add more tiedown points where needed, and an aluminum ramp door threshold plate should finish it off.