We traveled to AK with our MH and toad in the summer of '09. It was nothing like all the horror stories I had heard. The Alaska Highway through Canada and into Alaska is a very nice roadway. I found the vast majority of it perfectly fine 50-55 mph highway. You could go faster, I suppose, but take time to enjoy the scenery!
Yes, there are places with road construction (rebuilding) - you simply slow down and take your time over those gravel areas. We had been told that if on a gravel stretch of road and a vehicle was coming at you at a high rate of speed to slow down, pull over to the far right - stop if need be - and then continue.
There is an ongoing major problem with the Alaska Highway in the Yukon between Destruction Bay and the Alaska border. Some years ago, during a road rebuilding project, the construction company dug down too far and got into the permafrost layer. It has been patched up many times and a permanent solution is in the works. Maybe it's finished by now.
Frost heaves - There always will be some. Found that almost every one was marked by an orange cone or marker of some sort at the shoulder. Be aware of them, watch for a marker and slow down. One neat warning system is to follow another vehicle. When you see the back end bounce up and down you know there's a bump ahead.
Availability of fuel is not such a large concern. The main paved, traveled roads have roadhouses spaced out where you can eat and maybe park overnight. Most seemed to have a fuel pump outside somewhere.
In summary - don't rush. The scenery is too grand to miss out on - use the pull-offs to get out and walk around and take a look! Be aware there are hazzards (like the nut behind the other wheel), but don't let stories get you too tensed up to enjoy the trip.
'14 Winnebago Vista 35F, '14 GMC Terrain
BlueOx Towing Pkg, SMI Stay-n-Play
49 States & 7 Provinces visited in MH | WIT W112365