^^^^^ummmm yeah if you cant fix warpage i highly suggest you do not attempt to reskin the door warpage is NOT that big of deal..for the price of buying a new door you could have a bodyman straight'n it
yea man, ide just go and pick a new door up, the guy i got my chevy from warped the fuck out of the door too, so theres a crap load of bondo on it. oh well, i got a whole new cab with new doors for it.
so the process of heating it up and putting dry ice on it to cool it down is the same as heat shrinking. you might as well get a torch like an oxy torch heat up the metal in about half dollar size circles pound out the dent and cool it with a wash cloth diped in cold water. faster, cheaper, and your hand wont get frost bite