Lower Rear Quarter Patch Repair

Ok I read back through this tread a bit, and have a suggested plan for you. The pros can feel free to correct me.

Taking into consideration the size of the weld, the area of the car, the curvature of the panel, and your admitted skill level I would suggest a different approach. Cut the panel about a half inch above the top style line and use an Eastwood panel perfect tool. It seems gimmicky, but works excellent. You don't want to be working out in that open field above that style line. That's a compound convex area. Right above that style line will be less prone to warpage as the style line adds some rigidity to the area. The panel perfect tool will also add rigidity and give you a recessed weld. Not only will this help you with welding/warpage, but will help you tremendously afterwards (little to no grinding, and minimal filler work).