Kritter, We have the same camper, and we are also going to change the mattress. One thing to keep in mind, is that a standard queen sized mattress is 6" longer than the one that is currently in the camper. I am going add a 6" hingeable extension with some folding leg supports. This way when I retract the slide-out, I will just need to fold the extension up and hold the end of the mattress up so it rests on the dresser when in the stowed position.
Retired Army CW4 - "Waterborne"
2005 Chevy 2500 crew cab with Duramax/Allison
2014 Lacrosse 327RES
Days camped 2014 - 0, 2015 - 24