Welcome to the Forum, SlammaJamma.
If it were mine.....bear in mind here that I am in no stretch of the imagination a "Purist"....I would install a .032 overlay patch - probably about 6" X 6".
Drill all of the holes and preinstall with Clecos to insure a fit, then put a goodly smathering of Vulkem or similar on both sides to be mated. (Moderators take note - I did not say "Vulkem the cr@p out of it.)
Then install with Olympic rivets - you could buck the rivets, but several interior panels would have to be removed to get a backing bar to the repair site. I would suggest a rivet about every inch around the perimeter.
Below is a before and after of a larger Overlay Patch I installed on the 78 Sovereign
to hide an "uh-oh" perpetrated by the PO.
Edit - Be SURE to stop drill the ends of the cracks.