I know its hard to do in another way but winning the coin toss in OT is more or less a free ticket to victory, a coin toss should not have that impact on a game of this magnitude.
I always thought overtime, in playoff games should be like this;
No coin toss.
The last team to tie the game up gets the ball kicked to them first. However that drive ends (score, downs...), it ends and they then kick it back (no punts) to the other team.
If they are still tied at the end of that, then repeat until a winner emerges.