I don't think you can do that persay, but what you could possibly do is upgrade your entire camera, with a forward and reverse camera. As there is a control module to tell the camera when to go on and off. Here is one from Alpine:
Alpine Electronics of America, Inc.
I'm not 100% positive it is plug in play to an OEM Nav unit but you could read into it. And below is their entire drive assist line.
Alpine Electronics of America, Inc.