I'm still trying to picture the retaining clips in the side panel before I start to pry. I seem to recall pulling off a panel on the driver's side door many years ago and it was a wire-like spring clip that protruded perpendicular from the panel and passed thru and undersized hole in the metal on the door. Is that the type of clip you recall seeing?
If yes - then I assume that I need to slide a flat bar as far as I can under the front edge of the panel and pry away from the side (towards the opposide side of the car).
Does that sound right?