I don't have on in front of me, but I'm pretty sure that when you make reservations for another, renting or not, THEIR name appears on the confirmation and the reservation, even though the confirmation form is mailed to the owner.
Thus, the ID check at check in would work.
Somewhere in the documents is says that members are supposed to tell MS if they are making a "rental" reservation, but I don't know if that information is passed along to the resorts, or if they pay attention to it.