thanks!
No way you're gonna solder tank with electric iron. Not enough heat! Silver solder's awesome stuff, used it to build racing bicycle frames decades ago. But it's only for close-fitting lugs and not good for gap-filling. Minimum to get necessary heat is small crème brulée torche. Or small portable Bernzomatic oxy-acetylene unit will work as well.
Best to braze hole shut with brass. Will also need that kind of strength to re-attach bracket. Solder won't do.
Link to original page on YouTube.