I know you stated that they wouldn't have to necessarily be early tomatos, but I think that would be your best bet.There are varieties that are bred specifically for cooler weather Oregon Spring and Glacier come to mind. Check out Tomato growers website for more. Also there are some that don't even need to be pollinated, so you could do them in a greenhouse or something like that. I grew Oregon Spring and it was good.

I'm also in SoCal. My Early Girl is still producing a half dozen tomatoes a week.

But how do they taste? Early Girl produces, but it's not that tasty even during the summer.

Champion - I had one monster of a plant (ok, I should have kept up with pinching and pruning) that kept bearing through the fall with no signs of letting up and I got tired of it (time for apples, pomegranites, persimmons and winter squash already!).
I have hangers on of Sungold, Momotoro, Costaluto Genovese and Jetsetter. I'm just waiting for the weather to warm up for them to get cranking again (otherwise it's off to the compost pile).

I've actually grown indoors and before I had decent lighting I was still able to get some tomatoes with Czech's Bush being the most productive. At that time I only had two 4' shoplights supplemented with three CFL's (60-watts each) hitting the plants from the sides.
As far as taste goes, Czech's Bush was good but on the acidic side for me. I prefer a more balanced taste. But it was productive. Also, I had started a thread on here about 2 years ago that a gardener from the Gulf coast of Texas replied to stating that he had good production from it even when it was hot outside. That's how my memory recalls his post anyways. I'm sure the thread is still around if you do a forum search of Czech's Bush, if you're interested in reading it.

I probably still have saved seed from it if you're interested. It's been about 2 years since I grew it. If you would like some my email address is SW2Driver@webtv.net.

Jeff

An update to my earlier post. Even though I know I saved seed for Czech's Bush, I did not label it apparently. I have two packets of seed I saved from when I first starting growing indoors. Golden Dwarf Champion & Czech's Bush were the two I know I saved seeds for, and it seems I have one of each, neither labeled. Which is unlike me. Regardless, I'll have to rescind the offer of CB. Someone emailed me requesting seeds, so I figured I better let everyone know.

Jeff

Update...

My Snow White came through! Apparently one of my Sungolds turned out to be a Snow White, and it has ripe fruit on it. Quite a few, in fact, and so far, very tasty. Sweet and fruity. I wouldn't call them pretty. They're a spooky translucent yellow-white with a lot of splitting.

The Matt's Wild Cherry I won't pull, but it is a total waste of space. They just won't ripen properly (by that, I mean, with good flavor) this time of year, not the way I grew them. They are small, bitter, have no sweetness, chewy. Spitters. I'll leave them on the vine until March when my seedlings are ready to replace them in the ground. Maybe they'll be better by then.

This is kind of what I was getting at with my title. Matt's Wild is definitely in the category of plants not to grow in winter months. Sungold and Snow White are okay.

My cherokee purples had flowers and fruit when I pulled them out last week...I hadn't been eating them, though, so I can't tell you about the flavor. I neglected to pull them in the fall, and after these rains, they just flowered again...

You might have good luck with the sun sugar hybrid found at the totally tomatoes site.
Bill

I had a Champion that kept going all winter, but fruit
was very small and not very tasty.

Also had a Kellog's Breakfast that grew all winter too
with nary a fruit.

I researched cold tolerant varieties before I planted in September. I had two Siberias and one Stupice. They were all very productive, although all were rather small. The Stupice varied from large cherry to current size. The Siberia varieties produced golf ball sized toms. They all had great flavor but the spidar mites got to them before I realized what was happening. I finally pulled the plants in December because they looked so bad. They were loaded with fruit but didn't ripen properly after the plants were damaged so badly.

It certainly was nice to have fresh tomatoes during the winter. I am planning on doing that again this year. If you choose varieties that come from northern/cold regions, you should be fine. The area nurseries have these available in the fall specifically for So Cal gardeners to grow during the winter.