Most people who get CCW in MO get a non-driver's license with the CCW printed on it. What this helps with is on a routine traffic stop out of state-- like Illinois or Wisconsin which has no concealed carry at all.
In MO, even if you have a non-driver's license with the CCW printed on it, the LEO will still find out you have CCW. You are required to show the LEO the CCW, whether or not you are carrying.
Also, in MO, you don't need a CCW to conceal carry in your car-- it's called "peaceable journey."
It doesn't have anything to do with plates-- just your ID.
Hope that helps...