The tip power is 12v, the camera we have has a feed that goes to the Tip from the power source. 12v should not affect the 720 as it is not using it for power, rather just a trigger.
The R-CAM port only uses the power as the trigger to override the screen and show the camera view. The Camera is what has the right and left mirroring in it.
I think you'd need to get a camera without the mirroring mode to make right - right and such.
Also, putting is in upside down will help the right and left, but then everything will be upside down. I don't see this helping.