PDR on Old Metal?
I have rods too for getting behind and under. If using the glue method, soak the new pull tabs in alcohol, then let them dry completely. Clean the panel well with alcohol as well. Use the biggest tab that will fit or multiple tabs. Put a 2x4 on the ground for the fulcrum and another as the lever to strap to. Not trying to pull too hard, but gently, slowly apply pressure instead of a slide hammer. Tapping the panel around the area being pulled with a plastic or rubber tipped hammer helps too.
Modern metal is so much thinner than 90s, much less 60s metal. If the PDR doesn't work, I use a slide hammer spot welder where I cannot get behind a panel. It works well but there can be no paint where pulled or grounded and the final panel will have some filler, just way less than it would have been. Needs a 10ga cable no longer than 50 feet from the outlet to be effective. The ground clamp is an electrode with a threaded collet. Both the gun and the ground are spot welded to the car, then the collet is rotated to make good contact to the metal or everything pops off on the next trigger pull. Disconnect battery or at least the alternator.