I believe OC is perfectly lawful in St. Joseph. But I think there have been reports of overly zealous local LEO's that have hassled OCers; even at gunpoint and maybe handcuffing them for further scrutiny. But that can and is happening in every state that allows OC b/c nosey, scared, pantswetting "concerned" citizens are calling in person-with-a-gun reports and the LEO's refuse to ignore the calls that offer no valid reports of suspicious or illegal behavior.
Also, a CCW from Florida at age 21 is perfectly acceptable in MO.
Edited to add that you should try a search of key words such as St. Joe or St. Joseph here and at missouricarry.com to see what is out there.