Jade, I'm looking too. The Gangplank appears to be the only liveaboard marina near the city, and I imagine the waitlist is years long. Any other ideas? Annapolis would be easy, but the commute to Rockville would be a nightmare.
I live near the Bay Bridge and commute to Arlington, Virginia every day. It's a tiresome drive, but there are people that travel to Arlington from the Eastern Shore! My ex drives to Rockville from Annapolis. Edgewater is a little bit closer than Annapolis and has multiple marinas. I know at least one has vacancy, as they just sent me a quote.