At the end of regulation, each head coach sends an envelope out to midfield with the captains.

Each envelope has a number in it written down by the head coach.

The number is the length of field goal that he is willing to bet his kicker can make it from. The ref opens the envelopes. The team with the highest number gets to attempt a kick from that distance. The defensive team can then select the end where the kick takes place. The defensive team can only rush 9 players. In exchange, no fakes are allowed.

Then if the kicker makes it, his team wins. If he misses it, his team loses.

If the coaches send out the same number, then do a coin flip. The winner of the coin flip decides if they want to kick or be defense. OR, you could send the captains back the sideline and tell each coach to send out a new number, but it can't be the same as the last number. And do this until you get two different numbers.

That's all.