:M **DO NOT GET AN AIR MATTRESS FOR ANY RV!!! ** :M
ok, sorry for internet-yelling. So, I did it for years, it was a massive PITA. Super expensive ones, cheap Colemans, they were all the same.
First - they leak.
Next, it's never the same pressure from one stop to another. As you travel up and down in elevation, outside pressure changes--the mattress does not. Unless of course it's leaking. It will be stiffer as you go up, flat as you go down to sea level.
Next - they leak.
And...cross a mountain pass, and you will be replacing it. It will pop. Ever had a bag of sealed chips in the car over a pass? Looks like a mylar balloon.
If you DO remember to let the air out before going over a pass, then you have to pump it back up to "Just the right" pressure again.
You going to use a hand pump? Battery pump? 110v pump? Bring one of each.