I think buying a mid-size cabin cruiser and doing a yearly slip would be the easiest way--no taxes, just fees to pull and launch the boat and whatever they charge for shore power if it isn't included in the slip fee. You could get a good sized boat (30'?) from the late 90s like this one:
http://nh.craigslist.org/bod/4612171936.html
...If you had a place on the water you'd likely have a boat too so the fact that you are paying maintenance on the boat is kinda a wash--just more expensive if it's a larger boat than you had planned on with a cabin. Only issue is no opportunity for making money on the deal and no family cabin to pass down through the generations. Those are becoming more and more difficult to come by.