Keep in mind that you can't shrink aluminum like you can a steel panel. It can only be stretched. So those 20 pings are already stretched into the body. Pushing them back out might result in a wripple around each one, or the result may be the ping pointing out.
Thus the need for panel replacement.
If they are on a straight section you can replace with sheet aluminum. There are a few posts on this forum about just that. Try a search for panel replacement.
1986 Airstream 345 Classic Motorhome