This is copied from the recreation.gov site for Colter Bay RV Park;
"Facilities
Colter Bay RV Park offers 112 full-hookup pull-through and back-in sites which include sewer, water, and 20-, 30-, and 50-amp electric outlets. Each pull-through RV site has a gravel parking space for one RV and one tow vehicle, with a maximum total length of 45 feet.* Each back-in site has a gravel parking space for one RV and one tow vehicle, with a maximum total length of 30 feet.* All sites include a picnic table, access to nearby water spigots, flush toilets, and laundry and showers available for an additional fee. Propane is available for purchase.
*Site sizes vary, please check individual site specifications before booking to confirm site accommodations.
I would call the park and double check to be sure.