I picture a crease in the fender sheet metal. No structural integrity to worry about beyond just fixing it. Most times a truck gets hit/pushed in and forces the fender back and that is what makes the door hit. If it's a hinge problem, the pin/bushing is worn and changes the pivot axis centerline. If you can not get behind the crease or don't want to dis assemble fender, the pull out may work with filler applied. Welding should have a backer behind unless you are real good at it. (Either with slicing crease and welding or patch welding). The old, cheaper, pull out method is a slide hammer but leaves holes. I'll bet if you google "crease repair" and such , you'll get a Youtube or two. I've seen a guy stick his stick welder stick to the body, slide a short pipe or socket on the stick (electrode), put a vice grip on the end of the stick and slide hammer it with no holes left.(poor man's stud welder). The stud weld idea will be very risky because you WILL pull it too far and then what do you do? You can't hammer it back with no dolly behind, and as said, it's stretched already anyway. It'll be like chasing an air bubble around inside a decal. I've also read funky (in a good way) ideas on here of slicing the crease, grinding the head of a nail to fit into/behind crease slot, turn nail and pull crease back flat. Slide a washer on nail shank and pull with claw hammer? I said funky didn't I. May this will give some better ideas on that theme.
