I did more bug-hunting. While I couldn’t find out what stops the bartender from spawning, I’ve found out where the barber keeps disappearing off to. The barber somehow spawns by himself in a different ranch (I found this completely by chance). Someone who knows the code better than I do should find out what’s going on.
How about caravan escort missions? 4-5 npcs need to be escorted to a refugee center, survival outpost etc. The outpost should also have a market, general store, where items could be bought, traded. I like really this idea!