Tips needed-backing up on the passenger's side.

I've been towing for many, many years now and still have difficulty backing on the right side. One thing that works for me is the passenger side mirror. Mine has the motor in it, so when backing, I can change the angle of the mirror so I can keep it on the trailer passenger side wheels and ground as I'm turning and backing. This is the only way I can do it (and I still have difficulty. I usually cut it too short. Someday I'll conquer this ... someday ... I'm not giving up!)