If you heading north on Rt 1 a few miles north of Cambria ,the San Simeon SP. has a "primitive" area Washborn camp it's up on the hill about a 1/2 mile from the beach but has great views.
It's usually not full.Although now you cam make reservations.
Other campgrounds along the coast north of there to Monterey are usually full.
There is a campground in Monterey no reservations,Veterans Park up on the
hill at the end of Jefferson st.
Nice place, showers ,oak trees around sites.
Above SF you might score a midweek site at Samuel P. Taylor SP. It's close to
Point Reyes National Seashore.
If you are heading all the way north on Hwy 1
there is a beach camp at the Navarro River where it flows into the ocean.
Also a camp a few miles north of Ft Bragg Westport-Union Landing SB I think
you can pull over and camp there.
Good luck have fun.
Frank