I have a 2016 BT cruiser 5210. It’s my understanding from the previous owner, my backup camera was intermittent like that (not just at night). Eventually it stopped working completely. The radio would just go black when i put it in reverse indicating the reverse switch was working. Radio screen worked on all other modes so display was fine. It has a RCA video cable running from the head to the rear camera. It turned the cable ran under the coach and made it to the rear bumper. From there another 8 foot cable RCA plugged into it and went up to the camera. That short cable chaffed and eventually broke which caused an open video cable to the camera. I replace the wire and it works great. Poor design, my RV only has 14000 miles on it. I put the new wire in a sleeve where it makes the bend upwards.
It was a pain pulling the radio out to check continuity. i had to put the dash completely out.