Just looking at Canada and Alaska after Dawson Creek, 7 to 9 hours will get you 350 miles, 10 hours will get 500 miles. We stop every hour or so for about 10 minutes. The two slowest areas are Ft Nelson to Liard Hot Springs, mostly due to road alignment with a lot of hills and curves, and Kluane Lake to the border due to frost heaves and construction. The main roads in Canada and Alaska are pretty decent, mostly 12 wide lanes and shoulders. We plan to average, including stops, between 45 and 50 miles for each elapsed hour of travel. It has been pretty consistent over the last 8 years.