Go to Municode.com and look under St. Louis Cuonty. "Afton" is not really a city or town, it's a census designated place. In other words, pretend it doesn't exist.
As for OC, the overwhelming majority of officers in St. Louis County tend to think a current law that says you must receive written permission and have it on you while on another property, is what they will charge you with if you open carry. This is the response I got from every precinct in the county and that is what they are talking about on their "county brown" forum.
I think it could be beaten because it violates the preemption clause in the state statutes, but you will still go to jail, lose your firearm, have legal fees, have to take it to the court of appeals, and maybe come out the "winner".