Winter here still has more reliable VMC than British summers.
You don't need to cross the Sierras to get to Death valley from LA.
People regularly fly VFR to Tahoe and Mammoth for the skiing through the winter.
Weekends are usually easy to cross the China Lakes restricted areas with Joshua approach.
An alternative route from LA is up Owens valley north of Mojave and Inyokern and across Saline valley and down.
If you tell NorCal that you want to do a bay tour, they'll usually route you lowish along Silicon Valley and set you loose below the Class B from downtown SF with Alcatraz and the Golden Gate in front of you. Turn left and Half Moon Bay is a short hop away with no airspace in the way.
The LA FSDO is close to LAX on Nash St. Just get your paperwork in order, make your appointment and you'll walk out with a temporary airman's certificate.