We just upgraded our pop-up to a 2013 Keystone Passport 3220BH. We got a phenomenal deal and we LOVE it, but I must confess one disappointment: the queen mattress in the front bedroom. I put a thick, dense foam topper on it, but it's not enough. I think we might have to replace it before we take any extended trips - I don't think my back could take any more than three nights on it. Has anyone out there purchased a mattress for their RV that they recommend, or any suggestions for further enhancing what I have?