I wouldn't do this same day for reasons as above: the earlier flight not only doesn't guarantee that mech/weather could still mess things up (albeit less likely), it also eats up your whole last day of vacation. Coming in the day before allows one last day in SF as suggested, and, if all goes completely to pot, you can still hire a car and drive up if absolutely necessary. SFO is my local major airport and it can be a total pain sometimes.

tb