I just found this video where some guy with a dirty finger shows a third-party backup camera on a 2012 Focus SE SFE and talks a little about the wiring. However he does not actually show its operation, so I don't know if he's hooked it into the center display (doesn't look like an MFT). There appears to be something on the left dash that could be the rear camera display.
I would consider the parking package if it didn't force me to get the leather, just for the rear-view camera. For that matter I'd get the premium package for the 6-way driver's seat if I could get it with cloth.