Point Reynes to SLO is too far if you want to take the PCH. I suggest that you stop at the HI in Monterey. This will give you the time to pick up CA1 around Santa Cruz. Leave Monterey early, drive down - and enjoy - the PCH to Cambria, by which time you will have seen by far the best of the coast, and cut across to Lost Hills on I-5. This will take you into LA, but it will be a long day.

Have you checked out this site for hostels?

Lifey