Are you going to update the OP soon about that open team slot? Also I have an idea for a new rule:
Each team gets 1 redo flag per game which they can use to redo 1 down. The referees will determine when a team can use their redo flag. If a controversial call pops up, the refs can ask if either team wants to use their redo flag. Remember this is just an idea, you don't have to use it if you don't like it.
You could also put in the rules that players can't prolong games by excessively arguing against the referees. Sure players should be able to point out their discontent about a call but don't prolong the game by doing so.