- To minimize spams: Since there is no local moderator at the moment, the child board will separate the trash, spamming and unrefined posts from the main board.
I think it would be much more beneficial for you to ask for a local moderator. You have several very active members who, if they are ready to accept responsibility, should perhaps apply for local mod positions.
Merit source applications to reward quality posts more are okay, but spam removal is perhaps more important for maintaining the forum. In the end, it will be easier for you to discuss if your board is spam-free.