I would do a little research about your neighbors and what they use their moorage for. If they use a lot of shore power, then galvanic corrosion MAY be an issue you will need to look into and be concerned with.
I couldn't disagree more with the concept of unhooking your battery. How does an automatic bilge pump function if you get a ton of water in there from a storm, blown off cover, etc.
Good advice on the cover. In case you don't already have a cover to fit a 220H, I will now make a shameless plug for the one I'm selling that I won't be using on my 220H:
clicky
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Paul
2007 Four Winns Horizon 220Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)