Motorcycle Towing

I have seen travel trailers and fifth wheels leaving bike week every year with a motorcycle trailer behind the camper. It doesn't look like a wonderfully great idea but, I have seen it. I'd want a camera looking at the bike trailer if I did something like that. Also, kinda looks like a funky train going down the road. Is it legal? Apparently so, in some states. I never looked at the hitches but, my guess is that they welded up a receiver to the frame or something like that. Although, I can't imagine there's a lot of weight on that hitch. When I pull my 900 pounds of Valkyrie Interstate on a trailer behind the Suburban I really don't feel it back there.