No, there is no extra charge for 'extra' people on your campsite.

However, if you are camping with horses and are bringing more than 4 horses then there is a $5/night charge per extra horse (over 4) for the extra pens.  We will make every effort to arrange for extra pens as close to your campsite as possible, but depending on your location in camp and how full the camp is, those extra horses may not be close to your campsite.