Due to back surgery, I recently purchased a MiniMax towbar for my RV7a. It moves the plane in and out of the hanger with no issues...even navigates a 3/4" hanger entrance rail with out much of a problem if I keep the speed up. I just have the plain 3 speed Dewalt version. It did take some time to climb the learning curve on how best to operate it.
Bob Cowan
RV7a, 400 plus hours