I've backpacked variations on the S2S trail a few times in the past 10 years, but never in January!
Most of the state park backpack camps in the Santa Cruz mountains have been closed November to April for several years due to budget cuts.
Possible legal camp sites more-or-less on S2S:
- Castle Rock walk-in camp might be open in the winter, call Castle Rock park directly (408) 867-2952.
- Car campgrounds near Big Basin Redwood State Park headquarters, but you already know about those.
- Jay Camp is a walk-in camp near BBRSP HQ, and might be open in the winter. Better than camping next to an RV. Hot showers nearby, bring quarters.
- Costanoa Lodge is much closer than Pigeon Point, easily reached by trail and a short stretch of dirt road from BBRSP, 3/4 mile from the ocean, with a variety of lodging and camping options. Not cheap. Be prepared for high winds. I treat myself to the Douglas Fir cabins.
The best map (by far) for this trip is the "Bay Area Trail Map: Saratoga to Big Basin" from Redwood Hikes Press
You'll have about 10 hours of "daylight" in January (tall redwood trees and a LOT of rain mean you'll rarely see the sun), so the long miles between these camps require hiking most of the daylight hours. But it's quite possible to go from the official start of S2S at Saratoga Gap to BBRSP HQ in one LONG day, then BBRSP to Costanoa in another long day, then touch the ocean 3/4 mile from Costanoa the next morning.