Pin holes in trunk above fuel tank

While I haven't even bought a welder yet, let alone figured out how to work one, I'm starting to deal with the rust repair on my 74 Dart.

In the spare tire well, driver's side, above the tank are some pin holes. Is there a good way to deal with this without pulling the tank?

If they weren't above the tank, and if they were in a flatter piece of the trunk pan, I'd just drill a larger hole and insert a grommet. But, I can't drill the hole without drilling into the tank.

I know fiberglass is less than ideal. JB Weld? Seam sealer? Anything?