I live aboard and work in Pittsburgh. It's outstanding in the summer.
Like Brian said some docks pretty much shut down in the winter. Find a marina that still has boats in the water
and talk to em. Long as they got some elec and h20 (that's not froze), you're good. I don't know why marinas
would have a problem with it, they're not making much money
in the winter.
You might not want to start the conversation with "I want to live
aboard at your docks" as some marinas frown on that. Maybe ease that into the conversation after you have assesed that there are slips available and are discussing prices.... IMHO