Do not concede any penalty infringements in a match
You might get this naturally, but there is a very easy way to get this.
What you can do here is use the edited teams (Under settings put all stats for your players to 100, and all stats for your opposition to 0) and simply avoid the ball going out of bounds and don't get tackled. Since you've edited your team to be amazing and their team terrible, they won't even be able to grab you to take you down. Simply stay on the field and keep the ball. You won't even have an opportunity to get a penalty this way.
With five minute halves, this will be fairly quick to head back to the sheds for a cold one.