Not sure which routes you are considering but we did the Alaska highway and Alaska to the end of the Kenai peninsula and back including the top of the world highway from Dawson City to Chicken Alaska in 2009. Our diesel had a 600 km. range (360 miles) with reserve between fills and I kept a spreadsheet of fills on a fill by fill basis. I noted that I did 391 miles between Whitehorse and Dawson City, I probably could have gotten fuel in between but at higher prices.
Hope this is helpful