Staniel Cay is not a good spot to leave a boat. In fact they ask you to leave the dock if a front is forecast. Sampson Cay, just north of Staniel is a lot better. Very sheltered. You can also leave a boat in Georgetown at the marina there. It's a bit bumpy and some slips don't have a lot of water but for a month it should be ok. If you want to leave it on a mooring, they're available in GT in hole number three. If you want to leave it on the hard you can leave it at Georgetown Marine in Master's Harbour. I would say Sampson Cay would be the most secure spot. You can get a lift (dink ride) to Staniel and fly out of there.