It's definitely do-able, it just requires some experience and fore-thought in order to run it right. I would not suggest your first GM experience to be that size for example... At least at the start, let it slowly grow to that size. If you already have GM experience though than go for it if you think you have the time for it. But getting Co-GM's would definitely aid a lot in keeping things organized, flowing better and helping the RP on track during the moments life might hit you hard.