We went to Alaska and three months was enough but not too much. There was never a moment when we had any fear except for possibly the fear of meeting a grizzly on a trail. We did carry bear spray that we bought at a Walmart's in Alaska.
Three pieces of advice.
1. Stop at Cottonwood campground on Kaulane Lake in the Yukon. If you call ahead they'll bake a loaf of bread for you. Kaulane is 46 miles long and two miles wide, surrounded by mountains.
2. Make reservations at Denali National Park and if you can camp at mile 30. The road in the park is 90 miles long. Mile 30 is as far as they normally let you drive in. Come with a full tank of water, It's dry camping. From there you can take busses thru the park for a nominal fee. The mountain is magnificent, you'll remember it forever. The bears are also a treat, we saw 18. There are no sources of food out there. When you take a bus ride you must take all your food. Not even a stick of gum is sold at the visitor's center at mile 62.
3. Go to the little town of Esker outside Fairbanks for the Northern Lights Show; it alone is worth the drive to Alaska.
Most important buy the Milepost book, available at many Barnes and Nobles. It details every mile of the trip, so complete you just won't believe it.
There is so much to see and do you'll want more time. I could go on and on. It is a wonderful place with much to do. We went alone and felt very safe. People up there are realy into helping.
You do need to recognize that you can't drive like you normally do. It takes longer to cover ground there. Some times the road slopes the wrong way in a curve.
Buy the Milepost before you leave and read it now.
Safe Travels,
Norm