I would say it depends on how long you are going to be there and the level of comfort you want.
We live in our 40' motorhome and have made the trip 3 times, staying in Alaska 3 months each time. As long a you drive the road conditions there are no problems. In fact, we took it as far north as Coldfoot twice.
The roads are not that bad, just take it slow and easy. The larger rig will allow you to be more comfortable when you stop. There are plenty of places to pull off the road and dry camp and sufficient commercial campgrounds for your size.
We saw numerous nights when the temperature got down enough for a fire. We watched people in pickup campers and very small trailers setting out around the fire, bundled up in coats, while we were inside the motorhome with our furnace running.
We are travelers, not campers.
If you are of the age and health to be a camper, then downsize and rough it. If not, then take the fifth wheel and be a traveler and enjoy your great adventure in comfort.
You can see our trip logs for the 3 trips in my signature below.