Some of the things I have built are two houses, multiple cars, garages, barns, furniture, mini bikes, livestock trailer, computers, sailboats, power boats, canoes, motorcycle trailer, etc.
Send me some money and I will put together a HF trailer, register it, tag it, and ship it to you in PA, OK?
If you are hung up on a "mail order trailer" you can go by a Harbor Freight or Northern Tool store and pick up the trailer in a box. I won't tell the "state" that you bolted it together. It is quite simple to do.
Vince @ SWFL or WNC
2015 Ural cT 2001 Kawasaki W650