Drilling holes and screwing in a slide hammer is about as neanderthal as it gets.............sure sign of hack body work. More prone to rusting and ruins good potential sheet metal.

For blind panels where you can't get behind for proper hammer/dolly work, take a look at this equipment:Autobody Store: Stud Welders This is just one source for the equipment, there are others if you search. Then go to youtube and search for "stud weld dent repair", lots of visuals to give you the basics to practice on. Note down the page linked above, there is a shrinking tip as well that works for small stretched areas, better control than a torch if you're not real experienced with live flame.