There is no loadout for killing Gunboats solo in a fighter, because fighters simply weren't meant to. But people with enough skill are capable of doing so, against cocky or bad gunboat pilots.
Inferno makes it a whole lot easier, because the hardest part is stripping a Gunboat's tank of a shield. If you're not an Outcast then it's a lot harder.
You could always use a pseudo-bomber loadout with 6 debs and a MR...