Allow me to chime in on Select Comfort mattresses. We are on our second "Sleep Number" bed and love it. Our first was an "extended queen" mattress in our last couple of homes. It was great, but the wrong size for an RV, so when we ordered our 2010 MS, we ordered the RV queen sized mattress from DRV. Granted, they had to put in an extra electrical outlet under the bed for the pump, but we couldn't be happier with a mattress.
The wife even has stated that she likes the RV mattress better than she did the home version. She especially likes it when it comes to making the bed after washing the sheets. It is much lighter to lift to put on fitted sheets at the head of the bed.
I suspect that one might need to have an outlet wired under the bed to accommodate the pump, but in our RV (with a queen sized bed), there are outlets on the wall on each side of the bed. One would also need to drill holes in the "foundation" for the mattress to accommodate the air tubes from the pump to the mattress.
Any Select Comfort store could probably order a person an RV King version or one might be able to get one online. Just be sure that you get the RV "Premium" model.
Here is a link to Select Comfort's RV mattresses.
Select Comfort RV Mattresses
Terry