Might a humble human make a suggestion to the august Council of Wyrms regarding Proposition 12? If only the winning Wyrm gains from the event then only the Wyrms in the most powerful position (in terms of humans eaten) will have any motivation to pass this resolution. My guess is that this would only be a handful? Which means that it is unlikely to pass.
My suggestion is to change it to a betting pool so that all of Wyrmdom can participate. Allow Wyrms to declare themselves contenders and allow all others to place bets on said contenders based on some set of odds you all can work out on your own. Then the give the winning Wyrm some % of the betting pool and pay out all the winning bets from the sums given in all the bets which were placed on losing contenders.