Mtz does recommend having the Telephoto a little on the driver's side, so that the angle of the windscreen points it more at the oncoming lane. If you mount it like this then it will be pointing at the wrong lane when rear facing, and you don't want it blocked by the mirror, so yes, a bit of experimenting is needed if you want to have the option to rotate it rearward. Also, I'm not sure that it is going to be an easy rotate that you can do while driving, since it will need reasonably accurate positioning, and I've heard that the rotation is a bit stiff, for anti-vibration reasons.