I keep my boat
at Fisherman's Village during the winter but us usually filled up during that season. They probably have room in late summer and if you dock
they might find you a place for the winter if you wanted to stay.
I spent a couple of seasons at Burnt Store. Not a bad walk to the showers/restrooms if you are in the south basin and reasonable parking. North basin can be a hike and parking is very limited. They have pump
out facilities at the dock
and one day a week they do the whole dock.
As has been said, Walmart, Home Depot facilities are about 9 miles