The stated use case seems like a good fit for tracks, +1 from me.
I have no problem with “v6” as a track name, but the usual pattern is to use just the number (6 in this case). As said, if you are sure you want “v6” that’s what I’ll create.
Since postman doesn’t have existing tracks, we do need to allow for comments from other reviewers for which we’ll do a 7-day waiting period per standard procedure. Thanks for your patience!
Unfortunately, not that I know of. Choosing a track is a conscious decision by the user, by design. One thing you could do is have the application you currently have on latest show a banner on startup asking users to manually switch to the v6 track.
IMHO it is up to publishers to choose track names which make most sense to their users etc (even if they are named differently than other snaps which make use of tracks) - so if Postman want v6 rather than just 6 etc this is up to them so +1 from me too.