I can definitely see the benefit of being able to move the camera around in multiple locations. But it sounds to me that you wired for 2 locations anyway (for 9V power); hence I am not sure if wireless is giving you any benefit over the video cable.

I re-purchased a better camera and took the view off the HU, into my 7" Mirror Monitor. Better equipment provides a much better view, especially at night.

I thought about installing another camera inside the van so I could keep on eye on my kids!!!