Might be a decent application for that Alumi-Pro stuff they sell at Vintage Trailer Supply. I wouldn't use the stuff on a structural repair, but this doesn't look like a particularly critical area. This is the stuff I'm talking about: http://www.vintagetrailersupply.com/...-p/vts-335.htm
Never used it, but I expect it would be at least as good as J-B Weld.
This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.