Looking at the alternative route through the Salinas Valley proposed by the ACA, I'm thinking of allowing three days to do this.
The first part looks fairly flat, so I'm thinking perhaps a 60 mile first day and stop overnight in King City. Any thoughts on this? Is this a good place to stop over? It has both campsites and motels.
After that the route is more challenging so perhaps a second day of 40 miles and stop over near Lake Nacimiento, again, there seem to be reasonable facilities there. Final day about 40 miles again into Cambria.
Any thoughts/advice appreciated.
Correct - the first part is fairly flat. Note too that there is a fair amount of ag traffic on this road. King City is pretty quiet these days. Yes, there are motels, don't know about the campgrounds, and haven't stayed in either in King City. As an alternate you could consider riding out to Arroyo Seco instead of shooting for King City. If you do, the next day you can skip crossing over to the east side of the valley and detour on Central Ave, ride a short stretch of 101 and pickup Jolon Road without crossing the river.
As for the second day, yes it is more challenging. Way fewer options for supplies along the route. There is no store in Jolon (at least there wasn't the last time I was there). There is or used to be a campground just inside the gate Hunter-Liggett - I don't know if it is still open to the public. If you go in the gate, you will need an official ID - not like the old days. There is a store at Lockwood. Continuing on, it's a pretty stiff climb to Lake Nacimiento. Facilities at LN aren't cheap and the boat noise on the lake can be annoying. But it's at least a place to stay - there aren't many options here unless you go into Paso.
As for the third leg, to go into Cambria, you can take Santa Rosa Creek Road. Has a short wall on it and a some steep tube-popping descents. It has also suffered some storm damage as well. Best to check locally before taking that road. Otherwise it's CA 46 to CA 1 and then you can choose whether to go north to Cambria or south to Cayucos (and Morro Bay SP).
Just one other word of caution - The Northerly wind blows mighty hard through the Salinas Valley in the afternoons. That's fine if you're headed southbound, but you northbound riders might want to keep that in mind and get an earlier start.