Since it is SFO there should be a reasonable chance something nice will be available, it's just a matter of how much the local office is willing to work with me since most will technically be "Dream Cars" which don't allow reward redemptions, even if the daily cost is lower.
In speaking with the local branch I was told it was too far out to confirm anything other than what the rules allow (effectively a downgrade to a Camero/Mustang). Since we want to begin our vacation instead of playing games at the counter they suggested I call back 1-2 days before at which point they would have more flexibility.
While I assume that was a way to postpone the conversation and make it someone else's problem, it's what I plan to do...as well as secure some alternatives in case they don't come through.