gosh its been awhile since you posted this...
I'm going soon for some winter camping and its too bad we don't have responses on this...

castle crags park. Great car camping sites. Near shasta and some great trails. I reccomend the trail that goes up to the crags very beautifull scenery and a real treat after a really awesome climb. I surveyed this trail you need no special gear, but i reccomend a good walking stick or two and of course your camera. The trail is mostly wooded till you reach the end of the treeline where the soil turns from dirt to rocks.

The whole of castle crags is really beautiful excursion and a couple days could easily be spent their exploring trails and enjoying camp.
shower and bathroom facilities. Included under the $80 national parks pass, i think tent camping is something like 10 or so per night.

I've got a couple more parks near the Klamoth [sp?] river if your going that far north.