Mike, could you post the route from a google map for us. The best I've got shows about 550 miles and at least 12 hours of hard riding in the twisties. I'd love to do it , but in my experience, that could turn into a 15-16 hour slog with a group unless everything goes perfect. Enjoying 36 to Hwy 3 and heading north there changes that a lot.
Well, I double checked the legs I'd thought about--Sac to Red Bluff, Eureka (Fortuna) by 36, Crescent City, and K-Falls, and you're a lot closer than I was. Maybe I left a leg out. The first 131 miles is just I-5 though, but still a pretty long day. And half of 36 is still 36, and we'd be taking them past "the sign." Maybe that's enough. I've never taken that route of 3 thru Hayfork to Weaverville, and I've always meant to try it. I guess it would be a shorter ride, and still a good one, but I don't know all the turns. Are you be going that way? It would help to have somebody who's done it before.