You can get around this pretty easily by just using a DVR and starting the game about halfway through. Fast forward through the commercials/breaks and you'll progressively catch up as the game goes on, and hopefully finish at about the same time.

The only major issue with this is if you have friends watching separately who regularly text you about occurences in the game as it's going on. You'll also have to make sure you don't look at any NFL websites during the game.