TBH, the more I think about it, the more I like this idea. I think it would be a great way to maintain such a massive clan happy and entertained.
Has anyone ever actually played in a 1 life all-on-all massive deathmatch? I have, and the most skilled players never win alone. The players that can gather the biggest force of friends to work together ends up winning, usually resulting in the most liked players winning, mainly because people will work together to kill people they DON'T like first, especially in this case they will go out of their way to kill people they fear have the skill to win a leadership position but don't want them leading. That's the amazing and fun dynamic this idea will bring.
You could just set leaders on your own and have this event on the side, but I think temporary leadership positions would make the dynamics of the events so much better, and if there is anything I learned from being a part of a 500+ member NW regiment, it's that such a massive group of people aren't going to stick together without a great deal of fun and entertainment being spoon fed to them through events such as these.
Not to mention, we had a very **** leader, both skillwise and tactics wise, but we still won just about every linebattle because we had the biggest lines. No matter how **** our individual members were, our large lines always triumphed.
Again, when you have that many members in a clan, they'll be too busy having fun with each-other than they probably won't even know or care who leading them. It's a very different experience from a very small competitive team that focuses only on 8 v 8 battles to win tournaments.