We keep ours setup as a bed full time and added a 4-inch memory foam mattress topper from Sams Club. Our 16 Deluxe has the big bed offered by Scamp
and if I remember correctly we purchased a Queen size topper. In order to get it fitted properly we cut it down with an electric knife. (We found a cheap one at Walmart.)
If you layout the memory foam on a clean surface and position the cushions on top you can use them as a template to mark your cut.
We now get a great nights sleep....... we use regular full size sheets and just tuck the extra under the memory foam.