Hwy 12 from Petaluma would get you to Hwy 1 at Bodega BAy. The Hwy 1 route from there North to Fort Bragg is kind of hairy for wider vehicles, being a VERY NARROW ROADWAY WITH A GOOD SIZED DITCH ALONG THE RIGHT SIDE OF THE ROAD most of the way from Jenner to Mendocino.
As windy as Hwy 20 is through the coastal redwood mountains, it is still a wider road with some turnouts that 1 North doesn't have, and a constant flow of traffic if you have trouble. I was once stranded about 7 miles East of Ft. Bragg on 20 and was able to get Verizon cell service - I would expect most of Hwy 1 to be without cell service. OK Hwy 1 is VERY SCENIC, but you can't enjoy the scenery while trying scared to keep your rig on the roadway.