I towed a 2005 Honda Shadow Areo 750 in the back of a 12(Maybe 14) foot enclose Uhaul from Denver to DC. I bought a bolt in hitch from Uhaul and I got 24 MPG average for the trip.
I had as much as 3400 pounds(GVW) in the trailer at one point and it still made it down the road. It didn't like it, but I only went a few, slow miles.
I have also towed my wifes car (VW Bug) on a flatbed for a few miles with it. The towing was done before I did any suspension mods at all.