How west? Are we just discussing BC or everything west of Ontario?
Rupertsland seems doable. Hudsonia maybe? Borealia? Selkirk(land/ia)?
Rupertsland wouldn't really work out after a point(people are going to start moving to Canada at some point), nor would Hudsonia-the main issue with the latter is that it's too local of a name to really apply well to the whole country, though it'd make a great name for a territory centered around Hudson Bay(particularly it's southern half, if you ask me).
Would be a great name for a northern territory but, somewhat like Hudsonia, might be just a little too localized to a particular feature to really work(Edit: on the other hand, though, although it's usually interpreted to mean "place of reeds", IIRC, it can also be alternatively interpreted to mean "place of grass" so there may be some versatility after all.)
. The OTL advantage that Saskatchewan had, I would say, was that the river it was named after was a fairly large one and could have been plausibly used for any territories between OTL Central Manitoba and the Rockies of Alberta. The Assiniboine River is rather smaller but the people who gave it it's name could potentially have been more spread out.....although it might take a fair number of PODs to make it work, I'd think it at least plausible, even if not super likely.
So, although it's not one of my preferred choices, I think Borealia might just be the most workable choice of any of the ones mentioned here-a rather large part of OTL Canada *is* still forested even today, after all, so the name is rather versatile, it can be used either for the entire TTL country or just a territory or province.
