I think you should keep it at level 70.
Who cares how fast you can get there?
Whoever gets there first actually cares about the contest and/or winning.
So I think you should keep it
You just want the money
But I can't monitor if people are hacking other than by my knowledge of how fast someone can level up.
Even then they all know the normal rates and can match it with hacks and go a bit faster unnoticed.