Limiting it to one per hour to the max of your empty kegs sounds reasonable. With the recent spellcasting stymie, I wonder what damage you think they can do now?
Kegs? Advies without spellcasting are pretty much just monster hunters.
I think you should only be allowed to keep one keg to be honest. But make that keg reduce your fatigue by 10 per use. Once you use it three times, it becomes empty. I can't even imagine an adventurer with a loaded cart full of kegs.
