Just a 'nuther thought on traveling da UP:
Back in the day, we yoosta follow the advice of some truckers, and used one of those little known Yooper secrets:
Federal Forest Highway FFH-13 from Nahma Junction (Rapid River) to M-28 at Wetmore was a virtual "Yooper Freeway", two lanes, paved, well maintained, little traffic (a bit of a lonely stretch at times, often more deer than vehicles, though!). We yoosta make some good time on that road!
It's been lotsa years though, so I can't say how it is today.
The same caveat may apply to what used to be a 'nuther good N-S route: M-95 from Iron Mountain via Sagola and Channing to US-41 east of Champion, at (I forget the name) "someone's corner".
You'd do well to get some recent local input on those two routes, though.