Something to consider are the fuel prices in Canada, you might want to stay in the States as long as you can before entering Canada.
I covered the front of my radiator with a bug screen to prevent gravel from hitting it. Not much you can do about head lights and windshield. I found most of the roads good, except for the construction stretches.
Watch out for the tour buses they don't slow downand are a hazard when they pass you, both coming and going.
Don't worry about break downs, the RV code for helping other campers is very strong in Alaska. Everyone will stop to help you.
You are going to cherish this trip.