We've owed a pop-up and are on our second hybrid. The mattresses in these things to us are not much different than the air mattresses we used when tenting. As said above, just throw a sleeping bag up there. We use a single sleeping bag laid out flat, pillows, and light weight comforters. All of three minutes to "make" the bed.
2013 Jayco Jayfeather X20 E, 2008 GMC Sierra 1500 Crew Cab Z71 SLE