Unfortunately, Sleep Number has discontinued sales of RV size mattresses. Standard Sleep Number mattresses are not rated for transportation safety but will fit in RVs that take standard sizes. -But where does that leave someone who needs an RV standard size?
Consider this link: https://www.theairbeddoctor.com
Looking to elevate either head or legs? Consider the Sleep Number adjustable wedge pillow. It is 8" max composed of 3 layers: one 4", and two 2" of different densities to customize for comfort. Use layers in any combination. Cotton, washable cover zips off with a zipper gusset to better fit pillow when layers are are removed. Contact Rosellen at 321-277-0135 or visit Sleepnumber.com
Here is another good resource, but their Sleep Number information is out of date. The Airbed Doctor | Air Beds and Adjustable Beds | Choose Your Sleep Comfort Number