What is your traffic like in Kentucky? The traffic in Southern CA is fast, extremely defensive to the point it's offensive ha ha, and scary to someone who isn't used to it.
I was able to safely drive us back from DLR to my brother's place in San Diego, but I was in a monster 7 seat Durango with a hefty engine, so many people just stayed away from me. It's my petite, girly sister in law's vehicle; she liked the noise of the engine so she bought it.

Oh, and I drove in the right lane the whole way, never venturing into a lane even close to the fast lane, b/c those people are, you know, fast.
Traffic jams in CA aren't stopped, they are moving, often well over 60, but as close together as you imagine a stopped traffic jam to be.
If I stayed in CA after graduating from high school I might have gotten used to it, but I fled...my brother left too (our mom moved) but moved to Miami FL so you can only imagine the traffic he learned to drive in! So he's fine in it, but I'm not, and I think it's fair to warn people from elsewhere, when they are planning on driving themselves up and back, that it might be a hairy experience.
As much as I love impromptu trips, unless you had a local driving you with a car at the ready (no waiting for rentals), I don't think I would do this half day trip. (cannot believe I just said that)
Also, if you're flying right into SAN, know that getting out of the airport in a car is hard. Every time my brother has picked us up, it takes about half an hour just to traverse the road to get to the streets to get to the highway. Seems there's always an event at Petco stadium, or it's lunch and the business people like my SIL are tryign to get somewhere, or it's after work or or or.