Please use your head if you park at Halfway gate. It's tight for space, and one of the things I'm concerned about is having it posted No Parking if too much spillover onto Sandwich Road occurs.
They just posted a bunch of No Parking signs at some turn-offs inside the Scussett reservation, and if Halfway gate gets to be a PITA it could happen there. And slobs leaving fish racks there doesn't help.
The Herring Run is your best bet. Roomy, well lighted, and IMO your car/truck is safer there than in some dark, unlit turn-off on the Cape side. Staties and Bourne PD are always driving along Scenic Highway.