I suggest you leave it until your car is ready for it's repaint. Don't go poking or scraping at it because if it's heavily pitted you could go right through. Then you will wish you hadn't touched it. The rust you are talking about is unlikely to be that bad if it's the underside of the top. Water can't really get trapped there. If you want to paint it with some chemical rust converter or red oxide primer, that's fine. I would just spray some cavity wax on it, and deal with it when you repaint the car. You probably can't buy cavity wax in your local auto parts store as you are in CA, but you should be able to get it from Eastwood. It comes in an aerosol can.
Johnny
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