If I owned a campground, I would charge a site fee based on size and hookups plus a per person charge with each site having a maximum occupancy. Example: $10 dry site or $20 hookup site fee plus $5/person. If you came on four motorcycles or with two truck campers, you would need to fit the space provided or pay for an additional site. It would be up to you to figure out how hookups would be used, since you are paying by occupancy.
Since I do not own a campground, I follow the rules that the owner sets or move on to a campground where I can follow the established rules.