"Indigo Bluffs CG" began as "Sleepy Bear CG" around 30+ years ago. We stayed there for a weekend the first year it was opened and met the owners (nice people). A few times since also but not since the new section to the west had fully opened. Not sure who owns it now. The original owners (can't remember their names as it was so long ago) lived in a mobile home which was also the office facing west as you went down the hill road and to the right into the CG area behind it. A simple cement block bathouse painted dark green but decent about 100 feet or so behind the mobile home with reasonable sized dirt sites (about 30 then) in a circle at the bottom of the hill and had 15 amp electric. The bathouse was on the south side of the CG against the hill. Entrance to the CG is still in the very same place today and the mobile home is still there.
We go past it about every year as we always camp at the Platte River CG in the N.P. a couple+ times each year. One of our very favorites. My nephew was a Ranger at the N.P. which was a State Park before it became a N.P. for many years. 30 and 50 amp flat paved very large sites in the forest with excellent tables and fire pits and many superb tiled bathouses with outside individually doored showers that are open all year and heated. The sites and paved roads are kept plowed all winter long and we love winter camping and no place better than SBNL to do it in! Next best is Tahquamenon Falls State Park CG in winter. With all the leaves off the trees, the deer etc are visible everywhere all day.
Th OP requested full hookups and that really limits the choices and more so in the U.P. That's why I haven't responded more. Full hookups mean absolutely nothing to us as all our RV naturally came with FW, GW, and BW holding tanks and they are good for a min of a week+ before even thinking about dumping. That's why they are there!
Indigo Bluffs CG It's on the N.E corner of County Road 677 (S. Benzonia Trail) and M-72 (W. Empire Hwy). Yes, the new section is very nice but it's higher priced also.
To the OP:
I'm trying to get a decent list of "full hookup" CG's in the U.P. close to major attractions put together for you. Some we have stayed at and some not!
I will repost the list of CG that are right on Lake Superior, Lake Michigan, and Lake Huron etc shoreline again. I've done it several times already. Nearly every one of them we have actually camped in over the last roughly 50 years. Some of them many many times!