If you check with Mini you will see that they don't recommend towing it 4 wheels down. However if it has the manual transmission, there doesn't seem to be a problem I suspect they just never tested it. A number of people are towing them including myself, and Blue Ox makes baseplates for the Mini. We are towing the Mini Roadster, and have a little less than 1000 miles of towing on it with no problems whatsoever. I have talked with others who have towed them for many more miles than us and they have experienced no problems either.
Ed Headington