I only remember one park along the West coast where someone told me I couldn't hang a hammock. I think it was Dana Point in Los Angeles. Most state parks are managed by retired people in RVs. They are not there to hassle you for no reason.

If you are on your own, you don't necessarily need a state park to camp in, just two trees somewhere off the road, and that is pretty easy to find in most parts of the West Coast.