There is one. Nacimiento-Fergusson Road.
It's advisable to call ahead to Ft. Hunter Liggett http://www.liggett.army.mil/sites/contactus.php if desiring to use the road across the base. At times, they close it off. I just looked at the Outdoor Recreation page, and the base appears to be open to hunters during the week -- after 5PM, till dark (and then some). I'd call Outdoor Recreation, first. Must have valid ID, vehicle registration and proof of insurance.
If coming from inland, it would be no big deal to be turned away, but if stuck on the Coast near Gorda and needing to get out, better have enough fuel to get back to wherever on the Coast, then back again to Jolon, then King City. There may not be fuel available at Jolon anymore. I think years ago it was removed(?) but there used to be a store there that might have had gasoline. Otherwise, from Jolon, go North to King City, or East to 101, then South to San Miguel and Paso Robles for fuel, not counting what may be left at Gorda, if you like paying more than double for it...
If I still lived out that way, I'd probably be thinking of driving to Gorda area to bring food and fuel to people I know who live there...
“There is one. Nacimiento-Fergusson Road.”
Yes there is, and I’ve driven it. While it’s a breathtaking drive, particularly the switchbacks that take you down to highway 1, but it’s not a road that you use to commute to work. You have to go all the way down to Hwy 46 to find a major east-west highway and it takes you to Paso Robles and 101. Or as you suggest, you can take Jolon Rd. From Mission San Antonio. Back when I was young and Vietnam was going on, you had to watch out for tanks crossing Jolon Rd.