[Steve/]

Not sure age is a good gage for when someone should tow. If someone is a good driver and pays attention to what they are doing then I would say they are good to go.
I worked with a guy and he was letting his 16 year old daughter tow their horse trailer, I asked if he was crazed, she would be destroyed if she harm a horse. He said that part of growing up.
Sometime later he came in and said guess what the daughter did, I said what. She was accepted by Harvard University, I guess he was doing something right. He did not know she had applied.