That's pretty slick! I had a "backup alarm" on my old Durango which worked pretty well. Ran my $60 or so at Costco about 3 years ago. Single sensor mounted on the license plate frame. Install tapped into the backup light, and a speaker mounted in the back cargo area to provide and alarm. It beeped once when put into reverse, then started beeping when you got close to an object, about 4'. Closer you got, faster the beeps until a solid tone at about 6". Your setup looks a lot nicer. I'd be curious to see what your setup costs as well.
TP