I just stumbled into this thread. Guys, I had the same issue for a while: intermittent blue screen/service rear camera message. Some days it would happen, some days it wouldn't.
This past summer I opened up the tailgate to install the kicker audio for the multipro tailgate. In so doing, I discovered what looked like an A/V cable loosely connected to a port inside the tailgate. It had a lot of slop to the connection. I secured the connection with electrical tape and have not had one blue screen since. Maybe I'm telling you something you've already tried/tested, but if not it might be worth your time to drop the tailgate, get out some torx bits and check the connection inside the tailgate. I was following this chap's directions:
Not sure if its the same access in the Silverados or not, but I gotta believe the interior electrical connections are the same.