We have a 2019 21C and U-shape dinette with Lagun Table. Our dinette bed is 83 in length (wall to wall) x 48 in width (wall to wall). However, the back cushion is heavy and difficult to move so we don't move that when we make it into a bed. In that case, the width of the dinette bed is (with the standard back cushion in place) 45 in.
Here are some items I use and like on our main bed:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
To cut off the bottom corner on the foam topper, use an electric carving knife. Nice and smooth fit. We like the foam topper. Very comfortable.
The bedding for the dinette bed is whatever sleeping bag/s our boys bring...but they prefer a tent so we don't use the dinette for a bed much. -Bea