I rode south from San Felipe about a year ago - rough dirt, lots of corrugations, some sandy patches, but extremely beautiful. There's petrol in the supermarket by the Bahia Gonzalez crossroads, plus great hotel right on the beach. Then there's Coco's Corner and the dirt comes back to the tarmac.
Cheers, suerte, Dan
Que el cielo exista, aunque mi lugar sea el infierno...