Unfortunately, it appears that you cannot tow automatic Minis 4 down. The owners manual for both 2007 and 2011 say that automatics can only be towed with the front wheels lifted or on a tow truck.
And as you suspect, I doubt you'd be able to use it on a dolly but it's not even because of the back end (although that might be a problem too). We've got a 97 Sebring Convertible (which I'm sure is higher than your Mini) and it barely fits on our Demco KarKaddy (it actually has some damage on the front lower fairing from putting it on / off the dolly and I had to cut away part of the front lower airdam so that it doesn't catch when backing it off the dolly but the car is 15 years old so it's not a big deal).