The ceremony is across the road from The Outpost Lodge (campground spot 40 of Cow Creek Campground). If you park in the designated lot at The Outpost, you are not required to have a state park pass on your vehicle. State park day passes are available for the overflow parking.
Receptionist is in the dome building next to the Outpost Lodge.
Also, the bar is cash only. There is an ATM on site but try to bring cash to save time and resources.