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There are two weep holes or drains on each lower corner of the windshield. They drain to the hollow of the fender between the vent and the outer shell of the fender. As "Rust never sleeps", it could be finding a way into the inner side of the vent wall. You could simulate rain to see if you can see where it's coming in. Worst case will be pulling your windshield...
Yeah Jon, I think you running water on her will tell the tale. May not be a quick task, but there should not be water where it's going.
If you used a metal hanger, you can cause scratches to the finish or rust proofing. If you get bare metal as a result it can lead to rust out. A vacuum or method that does not scratch the inside finish is best.
You can use those plastic drain cleaner tools for sinks and tubs. They are fairly long plastic and might work well in cleaning out those tight areas.