Best advice I can give is to not expect an "average" on any given day.
Some days the travel will go well, other days you may hit construction zones with lengthy waits for a pilot car, another day the frost heaves will rattle your teeth if you try to make time, then next day you might have 100 miles of rough gravel or dirt road, and then next week the highway might be closed due to a washout or forest fire and you'll wait it out.
Some days we've managed 100 miles in only 5 hours.
Other days we've put in 12 hours for 500 miles.
With the camper or fifth wheel, we poke along at about 40 mph unless the road is rough, because you never know where the giant pothole or unmarked frost heave will be. With my little car, I'll zip along the same sections at 80 mph without a second thought because I can weave, dodge and bounce through without issue.
When you leave Dawson Creek, the first 300 miles are darn nice actually. Biggest issue is the industrial traffic for the gas wells in the area.
The next 200 will be variable, with you needing to be alert for wildlife.
Then the next 100 miles, the bison will muss you up now and then. If they don't want to move off the road, they don't move off the road.
North of Watson Lake, Yukon, the potholes and frost heaves become more common so you need to stay alert.
