If you are not a resident of MI then you will need a CPL ( or some other form of license or permit) from your state of residence to have a pistol in your possession in MI. No CPL no pistol even if you are not carrying. MI only recognizes a CPL from the state you are a resident of.
http://www.legislature.mi.gov/(S(hjt...ame=mcl-28-422
(9) An individual who is not a resident of this state is not required to obtain a license under this section if all of the following conditions apply:
(a) The individual is licensed in his or her state of residence to purchase, carry, or transport a pistol.
(b) The individual is in possession of the license described in subdivision (a).
(c) The individual is the owner of the pistol he or she possesses, carries, or transports.
(d) The individual possesses the pistol for a lawful purpose.
(e) The individual is in this state for a period of 180 days or less and does not intend to establish residency in this state.