Cannot answer your question directly, but depending how bad the damage is, I know that some of the Paintless Dent Repair places can repair the side rocker panel. There are some holes in the underside of the rocker panel with access plugs and if needed some additional holes could be drilled.
If the damage is not severe it may be able to be repaired with PDR procedures.
This being said, I assume the metal may be the thickness of standard body panels.
jf- Well it certainly can't be fixed with a "paintless" pull-out-the-dent kinda system, it's crunched pretty bad. I'm going to the U-Pull_It junkyard tomorrow, guess I could measure various spots with my dial caliper. I know there's a beetle over there that's pretty mutilated.
When I weld I don't want to burn through the metal, hence wanting to know the gage. Dave