If you make this trip, take my word for it and go VFR only. Not only is IFR nearly impossible in Canada, due to the high MEAs, but you will miss the views, which is what the trip is about. (Also note that VFR on top is a no-no in Canada.) I left in mid July, and during the 3 weeks we were away, we only experienced 2 days we could not fly. We had to spend an extra day in Whitehorse on the way up, and the other day was one we hadn't planned on flying anyway in Homer.
You should get a copy of the Canada Flight Supplement and the Airport Facility Directory - Alaska Supplement. Sectional Charts would include Whitehorse, Anchorage, Anchorage VFR Terminal Chart, Fairbanks and Dawson. Depending on your destinations, you may also want Seward, Juneau, Ketchikan and Point Barrow. Canadian VFR Charts would include Vancouver, Prince George, Fort Nelson, Kitimat, Atlin and the Alaska Highway. These are available through Sporty's, or wherever complete charts are sold.
Most of the routes can be flown at 5500-7500 feet, and mountain passes aren't a problem in VFR. From Watson Lake on, you pretty much follow the Alaska Highway to Fairbanks. I would get a box lunch at Quesnel, as there is no place to get food until Whitehorse. You can get a nice lunch at Northway.
I can post GPS Flight Plans, and suggest hotels if anyone is interested.