I have no problem to turn my head and backup my big crosstour. However, having back-up camera is really helpful at the night.
Sometime in the parking lots, the camera shows me distances between bumpers. It's really easy. There was one guy watching me backuping my car. He was standing in front of my car and showing me a hand sign of "that was close" after I pulled out my car from the spot w/o turning my head. He probably had no idea I was watching screen while backing up. lol~