[ThePair]

We replaced our mattress with a 3.5 inch combo (foam on the bottom, memory foam on top. It is much more comfortable than the stock, and we can still close down with the sheet and a blanket (folded off the head side due to the florescent fixture as mentioned above.)

Some have replaced the mattress entirely with an aerobed, which seems even better, but I don't want to inflate/deflate each time. There's one couple that put in a Select Comfort mattress. I think they stated that they needed to take that off and put it in the aisle to close, but I'm not certain. Select Comfort now makes mattresses that collapse completely, for use in sofa-beds. If you could get one of those in the proper dimensions, I'd wager that you could deflate it and leave it in place, much like the aerobed, but with more comfort when in use. There's a similar product called "Air Dream" that might do the trick as well, but I've not seen one in person.