In Michigan it's required top inform, BUT
sometimes you don't get the chance. (Been ther, Done that)
After the LEO has finished I usually inform that I'm exercising a CPL.
Travel to other state, basically I follow MI law and inform. (unless its a no carry).
Have actually made a lexan rectangle with "MI CPL" stickers on it and will hold it in left hand facing the LEO. (after confirming actual LEO, there have been some instances of phony cops in MI.)