Well, you certainly don't need a 4WD permit to enjoy the fishing up there!
There are PLENTY of walk-on beaches with ample parking.
PICK *one* beach. Try to walk it at low tide during the DAY and look for structure. Mark your spots mentally. Return after sunset and after the wine-dark sea has covered up your spots. Make note of tide, moon phase, bait present, water clarity, etc.
Hunting for spots is half the fun of fishing, for me at least! When I get sick of the predictability of the Rhody rockpiles, I go to the Cape for some mental stimulation.
Make sure you get a free parking permit at CCNS Eastham Visitor Center.