Top of The World Highway?

You'll probably have better luck looking and asking in the "RVing in Canada and Alaska" forum. There's a current thread with some information there, in fact, though I don't know if any is from this year vs. last year or a couple years ago.

My understanding is that the conditions on the TOW highway depend as much on the recent weather as anything, and so any information now would be well out of date by the time you get there. In general, assuming it hasn't been extremely rainy, I don't see any reason to avoid it with a fifth wheel. It was fine in my class C a couple years ago.