5 in an inside will be tight. You will need to be VERY ORGANIZED, especially when it comes to the teen girls all their stuff and the BATHROOM. Shelf, storage and closet space is at a minimum.
Shower in shifts and take advantage of the showers in the spa.
Everyone will just have to be organized, pick up your stuff after you have used it. Everything in its place.
You must tell the girls that they cannot bring everything(you know what i am talking about) with them. Make them make a list of what they feel are the MUST HAVES for their cruise, sit down with them and go over it , whittle it down. Try not to duplicate anything. What I do with our kids is allow them to have one backpack for their personal stuff, what fits into that backpack is it, that's all they can take. It works wonders!