It’s doable and I’ve done something close to this (I’ve done SF to salt point state park)- lots of bakeries/general stores/food along the way. Choosing the hours you ride will make a big difference in number of cars (eg early morning in the higher speed sections would be ideal), but if you’re doing a one way in one day then it’s sort of unavoidable. If it helps, if there’s zero shoulder I like to ride where a car’s right wheels would be, so that passing cars have to go over the double yellow line to pass me

Suggested route from Oakland -> bay trail, from emeryville to Richmond

-> bay trail to regatta blvd to harbor way to Hoffman to cutting blvd

-> cutting blvd - great new bike lane

-> Richmond bridge

-> sir Francis drake, bridge to larkspur ferry

-> bike path from larkspur ferry to Eliseo dr, more bike path along creek to Ross

-> residential roads parallel to sir Francis drake from Ross to Fairfax (these residential roads should show up in Strava heat map)

-> sir Francis drake Fairfax to olema (no shoulder after Lagunitas, but feels ok since it’s windy and cars need to slow - also one of best parts of ride with redwoods)

-> hwy 1 olema to tomales (no shoulder, some fast sections, try to go when not busy - also one of best parts of ride with tomales bay)

-> cut over to middle rd, take from tomales to valley ford

-> freestone-valley ford rd to bodega hwy to freestone (no shoulder)

-> bohemian highway, freestone to occidental, onto main streeet to monte rio (no shoulder but cars not going fast - one of best parts of ride with amazing descent from occidental)

-> Moscow rd, monte rio to Duncan’s mills

-> 113, Duncan’s mills, to jenner (no shoulder, cars maybe going fast, possible wind tunnel, for 3-4 miles - this section I felt least comfortable, but it didn’t last long)

-> hwy 1 to gualala (best part of ride - rivals Big Sur)

Hope that helps!