You could probably find that info on the data sheet for whatever brand you're using (safest thing to do).
If you want a non-authoritative answer, here's one thought. If you cut/form a piece of scrap aluminum so it overlaps the opening by a quarter-inch or so, you can butter up the opening, press the 'patch' in place, & then 'butter' over the edges with a fillet of proseal. If you clean & scuff the area & the patch properly, after it cures you'd probably destroy the structure trying to get the patch out. It's pretty tough stuff.
FWIW,
Charlie
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