I am telling you, I warn and warn and warn about sandblasting panels and I will get over and over "I have done it without a problem".
The bad part is, IF it does get warped it is usually toast, ruined.
Cliff, you could possibly shrink the skins back with a shrinking disc.
http://metalshapers.org/101/jkelly/index.html But without a lot of practice or experience, this is going to pretty tough. Replacing the skins may be the only option. It really isn't that big of a deal, if the new skin is of good quality. I don't know what they are like, any ideas guys????
You would remove the skin as described in the following link.
http://www.autobodystore.com/ms3.htm But at the top you would leave an inch or so below the belt line, cutting it off nice and clean with a cut off disc. Then over lap the lip left with the new skin right up to just under the belt line.
Brian