I found mine a For Sale: race & performance cars, engines, engine parts, trailers . It was 1 year old. It was used as an office for a track photographer at a dragstip.I am interested too, first off how much do these trailers run, and where do you find them? That is a great set up.
He had decided to quit. He had the side window, breaker box, air conditioner, and counters installed. He threw in a 100" power cord and a 2 wheel dolly made for moving the trailer around by hand. I gave $2800 for it.
I recommend the dolly. Sometimes at shows they want the trailer where you can get it close with the truck but not in just the right spot.
Ususally anywhere that sells enclosed or horse trailers can get you whatever you want. My next one will have vendor windows in it.