There are some pretty long stretches of "not much" up there in Northern Ontario. I confess, I've flown over it MANY times, but some of those stretches of road are best missed (the standard driving route west from here involves cutting through the U.S.).
It's not completely impossible for Justin, though... I started randomly Googling for things up there, including service stations. Strategically picking stops in advance will be essential, as some of those runs can be long without any services at all.
Leaving Thunder Bay, for example, it looks like the next place to refuel might be Dorion (82km). From Dorion, the next marked services I found were 109km further along, on a loop off the highway called Rossport. There >IS< a populous area in the middle of that run, though, which I'm assuming is Red Rock. Bound to be something there.
After leaving Rossport, Schreiber and Terrace Bay are next (20km to Schreiber and another 14 to Terrace Bay).
Then there's a big chunk of "not much" until you get to what could be the aptly named "Marathon". 82km, and you have to come a couple of km off the highway to get to it. They even have an airport
White River appears to be next... another 95km run through the trees followed by another 92km to Wawa.
I could go on, but the rest of the trip doesn't look as bleak. What I've just described seems daunting enough.