All of my boat experience has been with freshwater. What kind of additional upkeep is required on a saltwater hull?
I also made some calls and you're right, some don't allow live-ins (but I found a lot that do) and there is a tier'ed rate depending on if you live aboard or not. Defiantly adds to the expense.
I'd probably just buy the boat outright so it would just be for utilities and the slip fee. The plumbing you speak of - would it already be potentially on a boat of that size, or would some type of modification be required in most circumstances. Hard for me to check these things out as hardly anyone in the great state of Nebraska even knows what a Sailboat is.