Just a heads-up for somethings you might need to consider.
We also have a 5th Wheel and purchased a new memory foam matress. Love it. But there can be issues. Ours is thicker than our OEM mattress. No issue while you are sleeping, but since my bed slides under the edge of our wardrobe closet by about a foot when the bedroom slide is brought in, we have to pull the sheets/blankets/comforter up at the foot end and fold them over to allow the mattress to slip under the lip of the closet.
Also, in colder climates, memory foam becomes cold, stiff, and inflexible until your body heat softens it back up some. We countered this with a heated mattress cover - just set it on a comfy temp 30 minutes or so before bedtime. Softens it right up. Then we just turn it off - unless it's really cold outside.