We replaced our mattress with a Serta 8" foam mattress in our Keystone and when we bought the new TT we put it in it . best sleeping mattress ever... here's a pic of the tag...
Since it's all foam, if you require a short queen, unzip the cover, remove the mattress and trim the mattress with a electric kitchen knife and put back in zipper cover and tuck the excess cover under at the head of the bed..
2015 Rockwood Windjammer 3029W Diamond Package
2014 RAM 2500 Laramie Longhorn 4 x 4
6.4 Hemi 410 HP, 410 Rear Axle