I just had one built a couple of months ago by a company in AR (Delta trailers). They did an excellent job. I looked at aluminum, but honestly there wasn't much weight savings and steel is considerably tougher. It is 6'6"x20'. I used tandem 7,000lb torsion (oil bath) axles, full drop rear ramp, led lights, and the best tires I could find. There's no way I could overload it with what I do.
The main reason I decided to go with steel over aluminum was I had a blowout with my old steel trailer. It would have beaten the fender of side off an aluminum, but it barely did anything to the steel.
I spent a year doing research on what I wanted before I had it built and I'm glad I did. There are definitely do's and don'ts.
