You didn't say what model MCI you have...
But in my MCI-9, the mirror has a base plate that screws onto the panel above the drivers windshield.
I use it all the time, from keeping an eye on my passengers to looking to see what fell out of the cupboards when I made a turn too fast...
Before my washroom was finished, it came in handy when I used it as a shaving mirror. Cut myself a few times going over those speed bumps. Such is life on the road...
Steve