Jim,
You can do this!! Get a very small tip and use very small rod, take it very slow so you don't get the metal too hot. don't use more than 8psi of Oxygen. Tack it every couple of inches then fill in the gaps. This is a very slow method but it works,especially on heavier truck metal.
Sometimes you don't even have to use a rod if you are careful. If you use rod hammer it down while still hot with a body mandrel backing up the hammer. This is an old tried and true technique, just remember to take it slow or you will get a nice warped panel. Shaped fenders are not so bad, but doors and large panels are bad news.
