Your trip sounds fantastic. I'm envious just looking at that long gravel road.
I'm sure you've thought about this already, and if you haven't you're likely to hear a good deal from the natives, but I thought I would mention a few things concering bear safety. Bears in AK and Canada can be really serious characters-- even the black bears. It's not like the lower 48.
(1) Don't leave food, or bags that contained food, cooking utensils, or clothing you cooked in within 100 yards of your tent at night. This is very important! Keep even your Bob bag away from the tent if there's any food residue or smell on it at all. Try to keep the food downwind of you, too.
(2) You might consider bear canisters to store your food in. They're pretty bear resistant, and would be worth the weight and the price if they keep your food reserves out of some bear's stomach.
(3) Make noise if you get out of the tent at night. Shout, or otherwise make yourself audible.
(4) You might consider picking up some OC bear spray in Prudhoe for the unlikely possibility of a close encounter.
(5) If you see roadkill or a larger dead animal near a prospective campsite don't camp there! Bug out, at least a mile.
(6) If you see a bear, don't run! And for goodness' sake, don't try to pedal away, even down a hill. Stand your ground, make reassuring sounding noises, ("hey bear", "it's all right", etc.,) then _slowly_ try to back away.
Bear (ugh) in mind that bear attacks are much more unlikely up in AK than in the lower 48. Much more dangerous than bears roaming the wilderness are those that rummage through garbage or otherwise have run into people and food before. So don't fret overmuch about it.