You can actually have more than one battle posted per day in the same way the Medusa Campaign worked. You personally can only post one. It shouldn't let you do more than that. However, if your opponent puts in your number and he reports it, then you can get a 2nd, 3rd, and even 4th battle reported just by confirming your participation in the battle. It isn't cheating if you do it that way. I believe the Nemesis Crown FAQ actually encourages more than one battle daily. I can't remember where though. In other words play as many battles as you can and have your enemies report the results.
For instance you can actually play the same gamer twice and each of you reports one of the battles. Once you have reported one battle though, it will not let you report another. Should you play another friend, he can report the battle and you just confirm it on the site. You still get the credit.
Unless you think this is sneaky, and underhanded. But then again, I am playing an Goblin army in the campaign too.