My understanding is that the group leaders are responsible for making sure that the people are following the MDC guidelines - making sure posts are relatively on topic, no ones being a total jerk, things like that. If it ends up getting overwhelming for you, we can always put it out to the group that we need an additional co-leader. By then there will probably be more people in the group so someone should be able to step up.
I should be fine through the fall - I'm a little concerned about the holidays though. I own a retail business so we get a little crazy that time of year. Might ask for a couple of extra sets of eyes around then!!