Air Mattress

When we were shown our 2008 Doubletree 5th wheel, we were told it had a king-size hide-a-bed sofa. Well, it doesn't, but it does have a two-level air mattress under the sofa. One level is full size, and the other level extends 21" past it. I am trying to figure out how to use this mattress. Right now I have too much stuff in the living room to play with it. Anyone ever have anything like this?