From what I understand, the group camping area is $10 per person, per night, minimum 20 people.
The regular campsites are maximum of 10 people with $2 extra a night for more than 2 adults.
If you are going value season, at $35 a night for a partial hookup, that is way less expensive than the group camping area, plus you have electric and water at each campsite.
They may have a regulation of at least one adult per site, so if you have 200 youth, 9 youth per site, that would be 23 sites, so you would need at least 23 adults.
There is also a regulation of no open fires at the regular campsites, except for in the grill. At the group sites, they have large fire pits for cooking.
It might be easier to feed the larger group at the group campsite.
Hope this is helpful
Carol