To answer your main question about throw covers, I bought 2 for the sofa in my TT. My dog likes to "dig" before laying down, and I wanted to protect the vinyl sofa from scratches. First one was a full cover: The arms of the sofa are so close to the sides of the refrig. and wardrobe in my slide, that I couldn't get the cover over the arms. Second was more of a "throw", designed to cover the cushions, but not the sides. It slides around on the vinyl sofa, and ends up being bunched up at one end or the other. I ended up throwing both away, but they might work better on a cloth
sofa. If you have a booth dinette, I would think that sliding in and out would also cause a slip cover to slide around and bunch up - regardless of the fabric. You may want to do a Google or Yellow Pages search for someone in your area that can sew new cushion covers in a fabric you find more appealing.