Cheboygan State Park is a short drive to the ferry as well. It's a tiny park, very rustic setting but they do have some sites with 15 amp service. Many sites are on the water, Duncan Bay, it is shallow and warm. Edit just read your signature, 38 foot + truck would be hard to drive around in Cheboygan SP. It's more a tent and small trailer CG. Like the other poster suggested, Wilderness is a proper RV park, even has full hookups at some sites.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed