I did a bunch of research on that area a long time ago. I recall the stage coach and the logging were both active at the same time. Those little towns and very tight rugged inlets were chuck full of lumber people cutting old growth down to meet the building demands needed in San Francisco before and after the great fire. Actually SF burned down more than once it was after the big quake 1902 and the big fire that the SF folks decided to get a handle on their water issue and the Hetch Hetchy plan was developed.
My 1920's place in SF is built of heart wood Redwood lumber thats blood RED amazing stuff you will never EVER see legally sold anywhere today. LOL Usal Rd was pretty important to that hey day logging and wagon haul road back then. The lumber was hauled down the coast by boat and some seriously insane salty sailors. Northern coast from SF all the way up to Washington is some of the worst coast in the world to transit by boat, hundreds of ships have been lost along that coast. I've raced enough up and down the coast to tell you the only time I've been beyond scared was racing a 27foot racing sailboat in 50knot winds and 32foot swells down the coast. We did just fine but DAMN you feel small when there is a 30+foot strait vertical fall to the water from the bow of the boat when your coming off the crest of a swell that big! Surfing them at 20+knots for 30hrs strait is one of the most epic rides one could ever have in their life! Been there done that. Maybe I'll do it again after my kids are grown and out of the house ;-)
Given how damn dry our winter was I bet my Subaru could do the whole trip. Its actually advised that you start at the north end and run South vs going North. Given choice between a SUV or Jeep etc or a bike - I would go with the bike hands down. Very enjoyable ride except when its wet which case its a hate mission you will never want to do again period. The big issue is with water and rutting of the road and mud making it a major hate mission but this spring and summer its probably the nicest that road will be given we are slated to have another 1997 winter this next winter which case very possible that Usal Rd could be washed out or wiped out by a slide and be closed much of next summer.
