I did take pictures.
Just checked the epoxy, which cured overnight. A pinhole formed, through which gas is still seeping!
Going to apply again today, and after the epoxy is hard (but not fully cured), I'm going to turn the tank right side up (but keep it tilted to keep fuel off the repaired area), and release my fuel cap overnight so that any vapor that builds up is released from that side. I did this on the first application but not the second, and I'm guessing that was why the epoxy weakened during curing.