Despite the warnings against using the Mobile Connector outside in rain, there was no trouble for me last year other than tripping the GFCI in the outlet.
Of course, your mileage may vary. I have a second MC that I leave at home, so if I permanently destroy one with rain I can still charge at home without having to stretch my Clipper Creek cable messily over the car while waiting for a new MC to arrive. A wall connector of course would work the same way if you have one (or a J1772 charger in a more convenient location than mine). And honestly, if the rain from a hurricane remnant isn't enough to damage it, I think it's a pretty low risk to leave it outside in normal Maine weather (just make sure it's not lying on the ground). Most likely the rain in Maine won't strain the phantom drain.
Now, In my case we've been using our marina for literally generations, so they know me, and they're quick to do what they can for a reliable customer who doesn't trash their boats. But I would go ahead and call yours to ask if they're cool with plugging in somewhere for a little extra cash. It's Maine, where (just for example) places that sell well pumps make a little extra by selling beer too, so it's probably safe to assume that everyone is up for a little side hustle. Plus it gets them thinking about installing actual chargers, and it won't be long before that will be a selling point for them.
If you end up just leaving the car there unplugged, you should turn off sentry mode. It may drain more than 2% per day.