The Trailmanor had three electrical-outlet-like things on the side of the refrigerator cabinet on a level with the stereo and above the refrigerator. But none of them were mounted in electrical boxes, they were just screwed into the Masonite of the cabinet side. As I was making the refrigerator cabinet airtight from the inside of the RV (not from the outside where the cooling air for the condenser comes from) I decided to install electrical boxes.
The cabinet sides are made from Masonite, and could be cut with a knife. All of the openings were enlarged to fit the boxes. These boxes have tabs that hold them in the wall, which deploy when you turn the screws in the corners.
You can see the Winegard digital antenna meter on the right of the photo. That turns out not to fit in a regular electrical box. Oops. Having already enlarged the opening to fit the electrical box, I had to modify a data box (one with an open back) by cutting it in half and screwing both halves on the other side of the Masonite from the Winegard meter.
I replaced the center panel, which had a phone jack, with a 6-position data panel. That will have connections for audio, USB, phone, and Ethernet.