Many things have been done to mask the issue, but the problem can most likely get worse and if it does, it can expand beyond the beltline trim so in reality all you might be doing is covering it up, only to give yourself a some extra years and find later that the issue down the road is worse. I'd deal with the issue head on and not cover it if I were in the same boat, and frankly, after having been out to our coach a few weeks ago, I may have some of what's been described where the sheet metal was cut.
If what I think is happening to our 2004 as many have pointed out here on this forum, it would be worth a call to Airstream and you know, if many of these have this issue, it's not unrealisitc that a class action case could be made, cause I can almost hear Airstream already....it's out of warranty.
Computers manufactured by companies such as IBM, Compaq and millions of others are by far the most popular with about 70 million machines in use worldwide. Macintosh fans note that cockroaches are far more numerous than humans and that numbers alone do not denote a higher life form. -NY Times 11/91