Worse case scenario would be three weeks, best would be two months.
I'm not too keen on traveling alone anymore, so it depends on how much time my riding companion can muster up. He owns a business, that he is trying to sell, but also likes to run marathons, so they are a big magnet to keep him close to home.
He does however, often mention that riding the Alaska Highway as his "dream ride", so every time a see him, I steer the conversation in that direction. Sometimes just be whistling Johnny Horton's famous song.
Take care, Bud