As the PP stated, most of the mods now have 2 queen beds, so this might give you the space needed to keep the peace. If not, you might be able to request Alligator Bayou at POR- they have a Murphy bed that pulls down for a 5th (child) occupant.
If you go with the air mattress it still won't be a problem as far as the resort is concerned. Just stand it up against a wall when you get up in the morning, so the mousekeepers have room to do their thing.