Some thought my idea of a 36 inch barrier wouldn't work to contain our 3 smaller dogs (2 terriers and a Jack Russell) but I'm happy to report it works well. I used a 36x48 inch sheet of plastic 1/16th inch thick, so it's very flexible, light weight, and being flat, is simple to store either on the bed or in the truck when underway. Fits many places in our 21 for keeping wet dogs off the bed, etc. I just tuck the ends behind open drawers, cabinet handles, and into corners to keep it in place.
We did get backside vinyl on our dinette cushions.
Need custom storage to your design? Don't drill holes!