Dear billi,
I'm no expert, but didn't Congress pass and the President sign a bill a few months ago equalizing treatment for both mental and physical problems? I think they did, and I think it's in force now. Lawyers are expensive, but you'd be a perfect candidate for your local California legal aid clinic, where they don't charge you. You might want to get an appointment there and explain your problem to a lawyer. If your insurance company gets a phone call from a lawyer acting for you they may have a real big change of heart. Insurance companies hate and fear lawyers.
Another thing to try might be to start a new thread in the BPD forum or sub-forum asking whether anyone on PC in your area of California knows a P or T who will treat someone with your diagnoses AS IF you only had an axis 2 illness. I know that in my area there are P's and T's who will do that. But my area is about as far from your area as you can get. The doctors don't make a big thing about this, they do it on the quiet because they really shouldn't. But many, many P's and T's are so sympathetic to their clients that they're really willing to bend the rules. Mine does.
If you're in a big city you're in luck, you'll probably have many doctors to find out about. If you're in a small town like me, there may only be one P or T around. Keep looking, keep checking, don't take one "no" for an answer. The world's a big place and people, even P's and T's, can be very different from each other.
The best of luck to you.
Take care.