I drive a 2014 GMC Savanah cargo van for work. It has a handy backup camera display built into the rearview mirror. However the camera is only on when the truck is in reverse. Seeing as how this is a cargo van with a solid wall directly behind the seats, the rearview mirror is useless for anything besides that backup camera display and checking my hair. I figure if I could get it to leave the backup camera on whenever the truck is on then I could also see whatever is directly behing me when just driving normally far more effectively than I can with just the side mirrors.

Is there any way to just keep the backup camera on whenenever the truck is on? Is there any reason why doing so would be a bad idea?