Why don't you have a Debate League applications thread? That way people can post an application that follows a template when they want to sign up with the understanding that you will be added when the time comes. Instead of constantly debating (ha!) over opening and closing sign-ups you'll just be able to add people on a first come first serve basis, as divisions need an extra person. I don't really see why anyone needs to prove themself worthy of being on the roster, none of the original members did it, all the need is the want and desire to improve their debating skills.
You already stole this thread from the graphics league, might as well steal another