I finally had a chance to get over to my Airstream. I tried loosening the screws on the trim under the window. I am extremely happy to report that it worked. The noise is not 100% gone but it's much much better. I can definitely live with it the way it is now. I'm so happy that my trailer will stay intact & not be cut open anywhere. I understand that cutting open the underbelly is not that uncommon or a tremendously big deal. But I was not happy with the thought of my brand new, VERY EXPENSIVE, trailer being cut open & patched up. Thanks to all for your replies. Especially Pat, who originally posted the idea of loosening the trim under the window. I'm a happy camper.