We tend to run to Alaska out of south Florida every two or three years. Not having any time restrictions on your trip, I think you will enjoy having the extra room of your TT. People that have lots of time seem to stay parked in one spot longer and day trip out of that location. Visitors with a more restrictive time line have to keep moving along so often enjoy a smaller rig. Our last four round trips have been with a truck camper, but the most round trips we have made were in a mid sized Class C bunk model. Have also used a pop up tent trailer, a Class A and a fifth wheel once. I have never found that the vehicle I am driving has much to do with the amount of pleasure I have received on the trip. On a normal summer trip, whatever that is, the truck camper works fine, but if it is a rainy summer, the TC gets smaller as the trip goes on. LOL
If you are comfortable towing your trailer here in the lower 48, you will do fine in Canada and Alaska with it. On our next trip north, we have talked about taking our fifth wheel with us, just to be more comfortable. Not really anyplace in our TC very comfortable to sit around in the evenings.
With any tow behind, make sure you have good tires, a couple of spares, don't have to be mounted, and that your axle bearings are properly lubricated. Also watch your overall load. Trailers seem to have more running gear problems than the self powered units. Builders are getting better at putting proper sized tires on trailers than they used to do. I have never pulled a TT to/from Alaska, but only because I have never owned one. We just take what we have at the time of the trip.