As a first time GM, he's being very smart. Limited OCC/RCC rules for him to be aware of on top of the combat & ability rules, and the RUE classes are more or less balanced. While I can't play, I commend OP for not chewing off too much. That said, OP, you might consider allowing the OCCs from the Mercenaries book since you're running a merc camp adventure. My group hasn't found that most of them are unbalancing while using them since first printing back in 1994.