Yes I did consider it (and even asked that very question on Pprune prior to my last trip!) but it will be an evening drive - possibly on a Friday and the general consenus was that at that time of day it would be a bit of a nightmare.
A standby from LAX to SAN is around $35 so I am considering going into LAX as you say then just getting a flight down the road.
However, checking flight prices it might actually be only marginally more expensive to get a confirmed ticket and avoid the risk of sleeping in the terminal
All the best...