We have a Tuft & Needle in our fifth wheel, but it's a standard queen - not sure they make RV sizes. (We like it so much, we put one in the guest room at the kids for when we stay there, too). A lot of full-timers in the Escapees club have been happy with the RV mattresses from this business:
Mattress InsiderWe're also firm believers in preventing moisture and mold and use this product under the mattress in the RV:
Aire-Flow HyperventRob