Did the whole coast last summer. "cycling the pacific coast" has info on every campsite that has HB camping. Basically, About 90% of the parks have HB sites. Some are awesome, some are awful. Im told they can NEVER turn you away, even if that means camping on the host spot. The only difficulty was that the park near encinitas closed down their HB site.... thus you pay for a full priced campsite.... but still not turned away.The other thing we would do is if the HB site looked bad, find 2 other cyclists and split a campsite, which sometimes are nicer. No reservations required.In a pinch, KOA's will sometimes offer hiker biker sites also for discounted rates, as one stretch didnt have a campground for 40 miles.My best experience was at some campground near Astoria, OR during Labor day weekend that was full with RVs for a civil war reenactment... hundreds of RVs, sold out weeks ahead of time. And we strolled into a peacful HB site all to ourselves with a dozen open spots!