I had failed to consider the whip, which the previous boss so conveniently drops at a 100% drop rate. Not only does it have the best attack out of any available weapon up to that point, but it also does full damage from the back row, and it has a good chance to paralyze on hit.
So Bartz is a back-row Freelancer for this fight, and now Galura is a pushover. If I get a paralyze in on Bartz's first hit, then everyone stays alive, and sometimes Galura never gets to attack. If not, then everyone dies except Bartz and we still win. Galura is hitting him for 0-4 damage a shot. It's still technically possible to lose if Galura gets 3 or so Rushes to connect on Bartz and drains his HP out, but it seems like a vanishingly small chance.
Looks like we get our date with Liquid Flame before implementing the Job system after all. I've mapped and pathed to Karnak.