Will your accommodations on Jost just let you store your luggage after check out?
Everyone has preferences for what they would do in your situation. You have a great handle on the logistics of your situation. You just need to decide how you prefer to spend your last day, how much moving place to place you are willing to do, how much you are willing to spend and how much stress you are willing endure for some extra beach hours.
You will figure it out!