I have one that I built out of a Harbor Frieght kit and a Sears cartop carrier. The first couple of times I pulled it, it was sort of scary. I have a hitch from HitchDoc and the instruction said know more than 40 pounds of tongue wieght. The trailor kept wanting to wag the dog. I added a swivel in the tongue (for those "U" turns through the ditches) and a rack to hold a 32 quart cooler. With the added weight on the tongue, it pulls a lot better. Probably more like 100 pounds on the ball. Havn't had any troubles with the hitch with the added wieght. Then again, I don't pull it but once or twice a year. I have gotten up to 75-80 mph before but don't reccomend that. I just had to pass some Harley riders that had some remarks at my last gas stop.
I have heard my clutch slip a couple of times when trying to gas choke it from a dead stop or on steep incline. Never serius, just had to back off the throttle a bit.
The Hitch Doc that I have is a permanate ball type. I have seen others that have a reciever that allows you to remove the ball. Much better plus, they make other things that will utilze the reciever as well. For instance, I saw a Golf bag holder the other day that attaches to a reciever.
Good Luck,
Bill