You should be able to get to MD on day one. If you can find parking, perhaps do what is suggested above and stay in a hotel on day one. By end of day two you should find campgrounds.
I've lived in RI and FL. I feel better about someone in MA going to FL than vice versa. At least you know what you are up against if a Nor'easter hits. Be flexible and watch the weather a week out. You have to be prepared to cancel.
Also, the DC metro does not plow/salt like New England. A light snow can cause way more problems in VA/MD than it would in RI/MA.