A word of caution from an old timer...
I have had a pre WW2 Miller HeliArc since 1972. Huge unit with 100 percent duty cycle. I was told by my welder friend who was selling it due to a divorce that it would weld one inch aluminum ... it came with a huge water cooled tip which I immediately changed out for a gas cooled one. It is AC/DC with infinite controls due to the screw handle on top moving the entire armature up and down. I love TIG and use Argon. None of that slag to have to remove... etc....
But this comes under the old saying of " If you are a hammer everything looks like a nail" .
Sometimes welding , as much fun as it is, is not the best solution for sheet metal repair. OR when using TIG or stick or MIG... you will need to basically use multiple TACKS instead of what you would think of as normal welding... this is due to needing to control heat warping of the sheet metal.... way better to control it than to have to correct it.
Sometimes butt welding is not even the strongest method to put sheet metal together.... the use of an offset flanger and hole cutter and Clecos along with brazing and solid steel rivets... since that may not take out the corrosion resistance the metal has designed into it..... and the ability to place the patch perfectly before attaching it... even though it may not be as much fun and might look like it was jury rigged together.... may actually be a much better repair.
so the rule is study sheet metal repair techniques before choosing the method of repair...
https://www.youtube.com/watch?v=lgEIVUVLrnQ
https://www.youtube.com/watch?v=6ZSxhj_2Avg
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Famous custom car builders like Barris often used tack brazing through holes on offset flanges with wet cloths close around the brazing spot to control warping. Like on the original BATMOBILE...
https://en.wikipedia.org/wiki/Batmobile