Unfortunately I have the same problem, except my rust hole is about 4 inches long and about 1 inch high, plus I have some bubbles under the fuel door. I've seen a lot with the same thing, but somehow have seen more without this problem. I still have to find a shop to fix it, but I think my best bet would be to replace the whole panel. My dad can do body work but it'* been a while since he has, and don't trust his handywork in this area 100%. And since this is my pride and joy, I'd rather spend the extra $$ to get it done right.
I bought some rubber undercoating the other day for the wheel wells.
Good luck. Rust is a B!@#$.