i hope your journey to our state is enjoyable! unfortunately there are a number of political subdivisions in MO that are not OC friendly.
Park Hills and Farmington are two of those places.
http://codes.sullivanpublications.com/codes-slp/ for Farmington....check Chapter 210 Ordinance Violations, Section 210.240
two other towns along that stretch of US 67 are Bonne Terre and Desloge. while i have OC'd in both of those towns and found them to be generally friendly, finding the relevant city code to offer you is proving problematic as the Sullivan Publications website just took a huge crap for me.
if it were me and i was just visiting, i would just exercise my CC option and go about my business. but there is a bill in the Senate this session that is hopefully going to give us full preemption this time around. cross you fingers!