Your best bet is going to be to get TWO single air mattresses.
Reason being is because no matter what size, an air mattress will more than likely only be rated for 300 lbs. Anything over that and you WILL start to have leaks and will more than likely wake up on the hard E floor.
Trust me on this, went through this with just about every mattress maker on the market so far when my girlfriend and I sleep in the back of the E.
We finally fixed this by squeezing two single wides in the back side by side. Never had a problem since.
Reason being is because no matter what size, an air mattress will more than likely only be rated for 300 lbs. Anything over that and you WILL start to have leaks and will more than likely wake up on the hard E floor.
Trust me on this, went through this with just about every mattress maker on the market so far when my girlfriend and I sleep in the back of the E.
We finally fixed this by squeezing two single wides in the back side by side. Never had a problem since.