The issue with that is, apart from food and drink, anything else that you didn't take to the water park with you, and instead bought there, you're going to have to take with you when you leave, and that means that you're still going to have to take everything on a bus from BB to DAK, then off the bus, then on a bus back to your hotel.
The only way to not take anything with you, and not bring anything back, is to use a MagicBand, rent a towel while you're there, and be prepared to go back to your hotel in your swimming costume.