Maybe this hullmod causes firing missiles to generate flux, but provide infinite ammo on cooldown.
Archean Order does exactly this, with ALL missiles. In that mod, all missiles have innate cooldowns and generate flux, sometimes MASSIVE flux, but have effectively unlimited ammo. Many missiles have very different behaviors and firing patterns than vanilla, allowing for spectacular missile boats that have no business in a melee due to their exorbitant flux generation. On the other hand, it also includes classifications of weapons like strike, assault, and fire support, informing what range they're meant to fight at. I wouldn't mind seeing a vanilla hull mod that alters limited missiles in a similar manner, though torpedoes would need significant flux costs and cooldowns to be even remotely fair.