I don't have one currently, how hard would it be to install?

 

I wouldnt attempt to add the OEM that comes from factory on the opted cayenne's.
Just go and buy a license plate backup camera frame and install the picture so it links in with the stock nav screen.

Yes, the facory camera I have on my GTS is great, and glad I opted for it, but as a 2nd option, do the suggestion.
It will cost you a couple hundred bucks, and you will be satisfied.

 

Where can you find a backup license plate camera that would link with the nav screen.. sounds awsum, I have a 2008 cayenne like the base model so no camera option on it but have nav, would be great feature to have something like that ay...