A) Giving people the ability to teleport halfway across the map. No.
B) Maybe. Still don't like the idea of teleporting.
C) You stated the issue with this one.
D) Going back to the old issues. No thanks.
E) Keeping the current issues. Still not ideal.
Simple fix would be to mark the retreat zone visually. I, personally, would like the idea of giving a warning similar to the torpedo warning when you are approaching the border, before the retreat countdown. This way people have extra time to react, without the problems increasing the countdown itself would bring.