The Campbell Highway is a difficult highway to travel. It is in very poor shape, not that it was ever in good shape.
The locals in Ross River are having problems travelling it between Ross River & Faro, doing damage to their vehicles. Ross River to Watson Lake is a tougher drive as it is all gravel and narrow.
We've enjoyed pulling our 25' fifth wheel while in 4-wheel drive to get through some of the mud pits. Mud to the hubs at one spot, literally.
So unless you enjoy slow drives, mud in every crevice of your vehicle, and unpredictable conditions, the Campbell Hwy isn't the route you want to take.
Also, Ross River sometimes doesn't have fuel. And we've learned the pay-at-the-pump at Faro can also be unpredictable. Faro has the only campground with services. Between Faro and Watson Lake there is nothing but gov't campgrounds. And you'll need to overnight at least once on that stretch. Impossible to do it safely in a day.
See some images here
http://suethomas.ca/CampbellHwy.html
