Fix this on the table, or fix it on your back under a car.
Aww shit, not quite enough steel left in there.
Clamp a thick piece of aluminum or copper flush against the back side of your blowholes. Then gently and with utmost finesse use that bastard like a firehose and flood weld puddle against the aluminum. Strike your arc on the backing plate, that way you won’t boil away the razor thin metal you’re trying to fix. Then roll the puddle over onto the thin bits and stop before you fuck it up. The aluminum also sucks up some panel warping heat.
Works for closing up chrome holes. Can also be done with furnace tape and a penny. ( tape will burn off but will hold for a couple seconds) Penny will stick but will pop off with your thumb nail. Also stay in school kids, any pay some poor bastard to do this for you.