I wouldn't try and full weld. Dozens of small tacks. Work opposites like when you tighten your lug nuts. When ur done you should have tacks no more than half inch apart. No need to weld around. I used to do this and then braze all around but that much heat causes too much warpage and the burn on the opposite side promotes rust. Found that once tacked all around just do your body work and ur good to go. If you want do first pass with gorilla hair ( oops my bad, tiger hair, I guess the gorillas have a better union). I work it so the patch is on the inside. If need be tack a piece of wire to the patch to pull on it to keep tight.