Instead of going from Saint Marys to Herrington Harbour which is some 68nm, I would suggest going to Solomons (42nm) and then to Annapolis (50 nm). In Solomons, you could either stay at one of the many marinas or anchor out. If you prefer to get a bit further up the Bay, pass Solomons and head into Hudson Creek, off the Little Choptank River. There are some nice snug anchorages (no services) in there. However, that is about 60 nm which is quite a distance.
Good luck and good luck in the race!