We are looking at the Outback 330RL. Saw it in person once and loved it, but now we don't have one close by to look at and we have some questions. On a rare occasion, we'd want a third sleeping area, and we wondered about leaving the table and chairs at home on that kind of trip and using a foldable 4" mattress where the dining slide is. I've seen some mattresses online, a full size is 54"x75", but we can't figure out what the floor space would be there without traveling a distance to measure in person. I can't find info on the depth of that slide. Would anyone be able to give us an idea if a mattress would fit? It would fold up during the day. Love everything about this trailer, except if we can't sleep 6 on occasion, it might be a deal breaker.