Rst repair

I have a 72 D/S that has a hole the size of a pencil eraser in the area just under the driver side of the rear window it's the only rust in the whole car and I would like to keep as much of the original metal as possible. How can I repair this with little to no cutting.

drill hole out a little bit to make sure you have clean metal, then cut a slug out of sheet metal and weld something on slug to hold it then mig it in, if you can get undernieth it you could use copper and just fill hole with weld.