OK - The first thing you need to do is quit thinking about Alaska being a destination and begin thinking about planning a voyage. Milepost is a must. Starting in Arizona, think about things to see and stops to make in the lower 48 as well. For instance, much of the drive will be mountainous so we planned ours by starting in New Mexico and driving the Rockies from there to where you drive out of them 3,000 miles to the north when you hit the Yukon. Used a different route back than the way up so we could see even more of BC and western US national parks etc.
Plan on no more than 250 to 300 miles per day and that leaves some time for stopping along the way since many sites are really take only an hour or two then time to move on. Twelve weeks is a good time frame for this type of journey. We have done it twice, in 2013 and 2019.
Denali starts going into fall coloration the last week in August and you can drive the fall coloration line all the way back to the US. The northern birch trees are just as beautiful as our aspens. Do plan on heading home from Fairbanks by Sept. 1 as many campgrounds that can handle a rig your size are seasonal and start closing down mid September.
Have fun planning and enjoy the trip (voyage).