Cost less to address the issue now, than it would once you have a hole.
Get a mobile glass company to come over and remove the glass for you, not sure how much that would cost.
Then take to the area with a wire brush where the rust is to reveal the extent of the problem. Then ive found POR15 to be awesome, recommended by JUSTCALLMEFRANK, works a charm. Hit it with that, then get the glass company to come back out and reseal the glass.