A regular queen fitted sheet will work if it is jersey (otherwise known as t-shirt sheets). It will stretch enough to fit. We don't use bottom sheets. I have thick coleman all cotton sleeping bags that will fit a mattress of that size when unzipped and unfolded. Nice flannel "bottom" sheet and extra padding. I used the jersey sheets for a while but found a true bottom sheet to be a pain to put on.
2004 Chevy Silverado 1500 Z71 4x4
2015 Flagstaff 205 Folding Camper