there's a network of quite good dirt roads going south from the top of naciemento-fergeuson. the South Coast Ridge Rd goes right down the spine, and there's a few roads off it. the ones that go off to the east run into Hunter-Liggett, so you can't go through, and most of the ones on the west don't go to 1. All of them are seasonal. I've not been there, but I've been wanting to go to Prewitt Ridge, overlooking the pacific, which is at the end of a bad road off the South Coast rd.
Prewitt Ridge is 3200' elevation, a big flat open area with nearly sheer drops to the coast on 3 sides. its an unimproved campsite. hangliders use it. so do downhill mountain bikers (they start there, and go down trails to the coast)
I found this video. its from the top of N-F road, and goes to the campsite at Prewitt Ridge... sped up 5:1 and its a 4x4 not a bike, sue me.
that video goes from (A) to (B) here...
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I believe you can ride to (C) and its mostly bad dirt jeep trails. this is *very* remote country.
see below. Plaskett Rd (C) is closed due to Mad Woman fighting public right of way. Use Los Burros Rd farther south.