Try doing that on 14GA and you're going to have nothing but seagull droppings on ruined sheet metal.
That's for 1/8" plate and up only.
No, these cars are stamped out of 18 GA.Are most of our cars 1/8 plate?
I always found it easier to fabricate the repair panel before cutting out the rust. You just should fabricate it a good bit larger so you have enough repair panel to cut out more than you think at first if rust extends further than planned.
Final cut with a special thin disc through both parts simultaniously will give you perfect gap for butt welding.
Why do we always now have to click on the Facebook LIKE button to start a video? Is this their latest tracking device? :rant: