In addition to the Milepost, pick up a copy of Mike and Terri Church's
Alaska Camping Mike is an Alaska native and Terri moved there after college. They have put together the most comprehensive guide I have ever seen. I read the entire book and put tabs on the pages for quick access. They give you routes and times/miles/stops, etc. Even phone numbers of campgrounds.
They update the guide every few years plus they have the latest info on their website.
My DH could not go over 6,000 feet due to a heart condition and that was never a problem in all of Alaska and Canada.
Dale