WHAT?   What's this about buying a tailgate?  I removed it so I can haul my truck camper ... the tailgate is in my garage?  
And the book does not explain removing the camera connector in an understandable way if you actually attempt to DO it, which I did.  And, yes, it is a true PITA to get your fingers in there -- the spare tire is in the way, and it means you have to crawl under the truck, figure out which one it is, and then pull it sideways with no leverage, and I can't fine a "Cap" anywhere near it.  There are THREE plugs there sitting together and you can't tell which one it is - three separate wire leads -- for you all suggesting me read the manual, Just read it - and then jump under your truck and do ONLY what the manual says, nothing else - and see how easy it is, well, it ain't.  The 2015 is different then earlier models, I'd guess, just from reading this thread. IT says nothing about "behind the license plate" - where in fact it is located, sorta, but you can't reach it because the spare tire obstructs it.
Ask me who wants to crawl under the truck every time you remove the tailgate - at least those of us who do it often - Like every time we camp.
QUOTE:  monkey44 needs to read his owners manual, the GM rear view camera is not a pita to deal with AND has a plug on the end of the harness to prevent any contamination from entering the exposed ends.