The only caveat to my statement below is that I am most familiar with SP from the coast north of Morro Bay to the Oregon border (Hwy 1 & 101) and many in the Northeast Sierra's from Chico north.
I have never found a SP in this region that didn't have several spaces in which your rig would fit. As you may know, SP do not have electrical, water or sewer hookups. Most have dumps as you exit.
There may be parts of SP you can't get into because a river separates the park and you can only use the section nearest the highway. Richardson's Grove, 101 south of Garberville; Grizzly Creek, south of Eureka (30' max); Standish-Hickey, 101 north of Leggett. In all the others you should be able to find a couple of spaces in which you will fit.
You might also be interested that many CA SP now offer WiFi. Check this list for more information www.parks.ca.gov/default.asp?page_id=23780
If you want hook ups, Morro Bay SP has several spots with 20 amp plus water (about 20 spaces).
Enjoy your tavels.