Don't know about the 'not in every guidebook' part, as there are some excellent books that cover your planned route.
(edited to add) You will have two serious issues to contend with: heat and poison oak. Stay flexible on your route, so if the inland temps hit 110 degrees F, you can ooze over to the coast. Buy a plant book with colour plates and get a positive ID on poison oak in all its forms and sizes. Not life-threatening unless you burn it and breath the smoke or cook food over it, but when touched it produces a VERY nasty rash that lasts for weeks. Some of the coastal parks in Northern CA have poison oak plants the size of small trees -- in other places it grows along the trails, even up the trunks of other trees.
Depending on your tolerance for small mountain roads (and the size of the RV), the Lost Coast area of Northern CA is very nice. Shelter Cove may or may not be worth a visit, but the stretch of coastline between it and Ferndale/Eureka to the north is quite senic.
Check out the Mattole road loop between Hwy 101 at Humboldt Redwoods State Park and Ferndale. In the same area along Hwy 101 is the "Avenue of the Giants" -- a tourist must-see.
Eureka is one of the few decent ports on the north CA coastline, so poking around there might be rewarding boat-wise.
Further north (just above Trinidad) is the Lagoons State Park-- both Big and Stone Lagoons are great, and you can camp at the former.
Last edited by Thorne; 06-29-2006 at 12:35 PM.
"The enemies of reason have a certain blind look."
Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.