Well, I think daughter is telling you she needs a bigger bed ..
You have the "Dance Hall Edition
".. no bath.. pretty expansive, eh?
It looks in good condition! A blank slate, you have a lot of room for creativity there. The new doors are a great start. You can have a shop make the cushions.. but it'll be spendy. If you are just going to use the set up as beds, you could try modifying a standard mattress, or just use store bought foam.
A bar fridge
would work since it sounds like you will have it set up with electric available most of the time (?) A coleman stove could work as a stovetop.
Put a seat near the door with a lid and stick a porta potti in there and have a place for one person to sit.. you could even do a short "Loveseat" thing there.
The rest is personal taste, new carpet or floor, curtains etc. The possibilities are endless!