Is it possible on this unit? If not, does anyone know offhand and god single din NAVs that do. Thanks.

Yes you can - on the faceplate press the "REAR" button - keeps the DVD player playing on the rear output - so you can listen to another source - you can loop the rear monitor out to the backup camera in and goto the SPLIT REAR & NAV screen so you can watch the video - have the gps and listen to another source at the same time!