We have went in the middle of the night in years past and went back to the gate to pay when they open. You will pay though, because they have a lot of people looking for the day passes on the dash. If you don't have one they will stop you.
Not that I know of.. on the days the clam boats are running I've seen the line probably 2 or 3 miles back up the road sometimes. property owners open up alternate parking areas along the way
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