All good advice, the other thing I would do, with tank out, would be a hammer test.
Same as you see the surveyorS do. Small ball pien hammer, tap all over the tank listening for the sound of thin/ aft metal spots. Or another 3/4 hole may appear.
Best to know now.
I wonder if we could have account of the number of owners and the age of their boats when they first had tank problems? I assume most of us that have not yet gone thru this, are about to!