I have a 1994 f150 xlt ext cab I'm prepping for paint, I had a large dent in my passger side ext cab panel I managed to pull out with a self tapping screw. (I know I know ghetto way of doing things) but I didn't see a reason to buy a puller when I had this at the house. Now I have holes in my panel, I understand that I can mig weld these holes shut. My problem is I read that I have to have a backing such as a pre80s penny, but I can not get to the rear of the holes (or I would have pushed the dent out). Can anyone give me advice on how to fill these holes up?