Ok, I already knew about the stall strip but never heard it called a "Y" spoiler before. Some with vetter fairings have thought about putting such a trip down the center of the front fairing to kill side winds but I don't recall anyone who has documented it in action yet. (memory bad on this though)
As for the "venting" in the same group above it has been shown the back end really just needs to be wider than the front to catch the air flowing past the gap / rider so it can reattach to the rear of the bike. If reattachment is the goal then this would have to be a must. If you simply wanted to push air over the gap then so far as I can tell no one has submitted a way to keep the air stream intact and have it reattach later.
So really if the goal is to "clear the gap" without "reattaching" then you don't need a proper tail as if the air stream doesn't reattach then it doesn't matter what is behind you.