I think it wouldn't be too much effort to leave a redirect at least for signups and potentially first round (do we know if moving a thread breaks pings btw?), doing it for all rounds sounds unnecessary to me though.
Wrt advertising Classic specifically, we already post the link in RoA, RBY/GSC/ADV/DPP/BW, and smogtours discord servers, the tour is advertised on PS through PS news, is pinned in an announcement in RoA's room, and appears in smogtours' roomintro. We also made sure it was advertised on our social media as well last year and I sure hope we'll keep using them for all official tournaments going forward. Of course if you can think of other ways to advertise official tournaments it's always worth to at least hear about it and see if we can work something out, but I think we should probably focus on extending our scope i.e increasing our presence in places where we can attract new players.