In 2019 I hitched from Olympia, WA to Arcata, CA. In Salem, OR my ride south on the 5 took me out to the coast, and I did the 101 south from Newport. The 1 stops pretty far south of the Lost Coast. Hitching was great, I even got housed by someone I met on a bus that stopped for me and gave me a ride for free! It was an all around good experience, I was leapfrogging with a few people on bike tour, but I didn't really meet anyone rubber tramping. It was mostly locals just giving me a ride to the next town south, over and over, until a boat dweller gave me a pretty long ride.
I also hitched the 101 north from Santa Rosa in 2015 when I got a ride from Berkeley, CA with a couple French Anarchist Vegan Lesbians I met at the Long Haul Infoshop who were really cool. So I've really only Traveled on the 1 south of the Bay, hitching out of Santa Cruz. It's still going in the North Bay, but I would recommend the 101 for hitching, I assume it'd also be better for rubber tramping. Towns like Laytonville and Cloverdale, CA were supper charming and I met great drivers there.