We did US2 from Mackinaw to Williston ND last Sept. We were headed for Glacier but it caught on fire ad the campgrounds were evacuated, so we headed south from Williston. We had no issues with cell service on Verizon.
It was a relaxing drive, but the MN/ND part was pretty boring.
However, the drone of the road is broken up every 1/2 hour or so by a town. You can tell a town is coming because the speed limit goes down, usually only to 50. Unlike the interstates, you actually see towns. We had a lot of fun reading each town's motto on the "Welcome To..." sign.
ND has some great state parks, We stayed at Devil's Lake
and Lewis & Clark.
Fuel was available as every town along the way.
If you'll be stopping in Superior/Duluth, try to spend a few nights at
Burlington Bay in Two Harbors. We didn't stay there but found it when we were exploring.
We stayed in Iron Mountain MI, Superior right next to the highway, then Bemidji MN, Devil's Lake and Lewis & Clark.
If you stop in Bemidji,
try Itasca SP and visit the headwaters of the Mississippi.