I knew you were from CA as soon as I read your first line. You beat me to it by seconds.

Another thing you can do is stop by the nearest USFS office, sheriffs substation, local CHP (or equivant in your area) resident officers place (or call the dispatch center to have the officer meet with you), fire station, whatever, to let them know your plans. If you are not parked toooo far off the beaten path they can try to keep an eye on your vehicle, and will know if you are late coming out. When you do come out be sure to recontact and let them know that you are alive a well...