Dealer quoted $700 to run wire for backup cam, Need Advise

I considered running it down, I just have not found any nice way to get the wire down the back of the unit. I didnt want to run it down the ladder or leave it exposed.

After seeing the guy who hid his wireless transmitter under the Ac Cover I may go that way. The rear view safety wireless transmitter matched to my camera is $190, Might just abandon my prewire in the truck and go simple...