I'm bound for Alaska again within a year, and in fact will be doing something along the same lines as what you are thinking of, this time.

That CGOAB journal is a nice read since they were there in the fall as well. Doesn't matter when you go the great north, you'll likely be wet often. Remember in your gear decisions that staying dry is nearly impossible when you are riding all day in pouring rain; staying warm will be the important part. Enjoy your trip planning!