If you decide to check out the Cassiar Highway then here is a site for you to check out.
https://www2.gov.bc.ca/gov/content/...driving-conditions/highway-37-stewart-cassiar
Road conditions on the Cassiar are much improved from when I regularly used it years ago. The road is now almost hard surface, with minimal gravel. Ore trucks still are on the highway, so drive like you would around gravel trucks.
Be very aware that while the road is scenic, cell coverage, wifi, and vehicle support is not going to be nearby. Fuel is available but repairs are only found in major towns.
Travel will be much less than on the Alaska Highway. I would recommend going up one way and return on the other. If you do take the Cassiar, make sure to visit Hyder, AK, the only southeast Alaska town you can reach by road. All others are by sea or air.
Enjoy the trip.