I believe when I launched last weekend they ask you if you are staying over night or just for the day. Can anybody confirm that you can leave your truck and trailer there for the weekend (over flow), I would guess there is a fee?
You can park in their lot for a fee ($5.00 per day) or there is a large and free lot just up the street from the gas station on the corner (5 minute walk at most). I parked in the free lot for a week and everything was fine. Lots of rigs and trailers in there.
The free lot is right across the street from the Greenport Motel. It is very safe and easy to get in and out. Good luck in the Derby!