Consider working with a manufacturer "in your neck of the woods" if possible. With cargo trailers, it seems to be all over the place. The majority of the well known brands seemed to be just that, brands, owned by an investment group. I purchased a Cargo Craft, and it had a few issues I thought it could have had a bit more attention to detail. After 6 years of use, however, I have to say if I were building another, I'd buy one of theirs again. They are one of the few privately owned (family) manufacturers left. They even sent a crew to my house to make corrections to the incorrect work order sent by the dealer on my custom options. In general, I'd say they offer the most for the least in terms of cost. My walls were 1" square tubing on 16" centers, roof at 24", no z-channel studs, screws were used for plywood, none of that crazy nail/screw head stuff.
Mine is an Expedition model, but with standard leaf spring axles from the Explorer to gain ground clearance. (Normal platform height is 18", mine is 22" (no 4" drop)
You mentioned BLM land, if you live out West, they have a plant in Texas, they even offer an off-road styled small cargo.

Example at Colorado Trailers
https://www.coloradotrailersinc.com/2016-cargo-craft-6x12-off-road-cargo-trailer-used-cargo-trailer-co-i2405314As far as "top trailers", Intech, Aluminum Trailer Corporation (ATC) both make all aluminum. I also like Homesteader built in Tennessee, (typical cargo trailer, but ones I've seen appear well built)