Rock a "CT MOPED" Plate which I have 1000 laminated copies of, and hope that you don't get pulled over by the police officer that's going to take the bike...
There is no way to register a moped in CT without going through a lot of hoops.
I have been in NYC for a few months and gotten stopped twice. Both times the cops were understanding that I was from out of state and let me ride off, but were implicit that if they had been a less relaxed officer the bike could be gone and I'd be in the back of the car.
But for rally times, I wouldn't worry about it.