Joed, what keeps the water in the tank from freezing? My grandpa had a cabin and he flushed the toilet to drain most the water out of it and then dumped just alittle antifreeze in there. He also used some in the bowl itself. I don't have a list of everything, but I know of a couple things he did.
1. Decon or mouse food.
2. Unplug refrigerator or trip breaker. Remove food. Clean interior with baking soda solution of 1 tablespoon soda to 1 quart of water. Wipe dry. Leave box of soda in frig and freezer. Leave doors open. Water supply to icemaker will already be shut off. (If you have an icemaker)
3. Shut he hot water heater off at the breaker BEFORE you drain it.
Below are a couple websites I just searched for which may come in handy. Checklists for closing up a cottage.
Below is a website of a company who closes cottages for you. Maybe if you don't feel like doing it you can look up in your pohne book if you have anyone like this or call these people to see if they have references.