Yeah, fuel would be an interesting concept where certain alcohols are more likely to attract certain customers. Definitely a good use for the nearly useless alcohol system we currently have.
The other option could be that you’re more likely to get patrons from factions that live close to your base with other factions rarer (but still likely). Kind of similar to the old purge, but still with the chance to get stuff otherwise. This would also still make it advantageous to visit other areas to recruit different thralls.