Just to add my two cents, mattress/memory foam is easy to cut into whatever size you want - head to Ikea and pick up a cheap foam mattress. We used a 2" memory foam topper (the one from Zinus) on our last RV and it really made a huge difference to the comfort of the mattress. Also it's easier to move around IMO. However, it shrank and pulled away from the edges about 3" and was always sliding around. This made the bed effectively smaller. But we are not a big couple, so it wasn't a big deal..