The definition of "tropical" is any plant that prefers a warmer climate than the one you live in. 
LOL - ain't that the truth!
It doesnt cost anything to be kind........
For some people in this forum, the cost of being polite is too rich for their blood... They choose to offend newcomers over and over again, and never change. And again and again, new people are turned off and leave the forum because they feel unwelcome and like they were publicly humiliated and made to look stupid for asking a question and being genuinely enthusiastic about loving to grow fruits.
Yes, one could have said it in a more gentle way, but technically, most of these fruits are not tropicals. I think it could easily be argued that any plant that can survive a freeze (regardless of where it originates) is not truly tropical, which means things like mangoes would not count either. But for the most part, I think people here are enthusiastic about all kinds of fruits (and also vegetables), and merely have a penchant for what grows in warm weather that they consider to be exotic - particularly things that like humidity and are not specifically desert fruit. But that includes a wide range of fruits, many of which may not be found in the typical grocery store outside of the true tropics latitude-wise, but also technically will not die with a freeze.
I would venture to say for instance, that some bananas are not really tropical, in that they can survive a freeze (or several), but that others are in that they really can't handle low temps. So it can be variety-specific, not just species-specific. A lot of species straddle the border, where some cultivars can take colder temps, and some can't.
Since you're open to things that are not specifically tropical, maybe these seemed obvious to you already, but you could include things like Olives, Almonds, etc. on the list. And many varieties of cacti. And grapes of course. But specifically muscadine grapes, which are a warmer-climate species.
The issue that you have is with not only freezes, but maintaining humidity, so I can't help too much with the list because I don't know a ton about growing tropicals in CA conditions. But, I do have a lot of experience growing various tropicals and sub-tropicals and even some temperates in humidity that never freezes with periods of drought.
Fortunately for you, there are a lot of CA growers here in this forum, and also zone pushers, so there is a good community to draw ideas from. I encourage you to push the zone and press your luck, if you don't mind losing a few plants, and see what you can make happen that nobody has before. People are discovering new things all the time. And sometimes, one particular plant can survive what the others couldn't, and you have a whole new variety on your hands. If you don't mind the sadness of plant death, failure is really success in my eyes. Failure is learning.
