For everyday backing up, the Framecam-on-spare is a good setup. You can tilt the cam straight down if you want but the spare is in your line of sight to the hitch receiver. I doubt you'd be happy with a setup like mine.
Hitchcam also sells a product called Unicam, which would proabably work perfectly for you and provide all the other rear-cam benefits, too. You could mount the cam on your bumper, just above the receiver?
http://hitchcam.com/