Nice state park campground
Sites are close, but the falls hike is beautiful. Fresh water, nice bathrooms with showers. Great place to enjoy a night or two, get some awesome hiking in, and refill water etc. Very busy, and unfortunately city people who played loud music when we were there.
Go farther up the arrowhead to find less busy or drive out into state forest campgrounds.
Great state campground
Enormous showers and real bathrooms, for when you're tired of put toilets. Great view of the Big Mac Bridge, although it does have some highway noise. Sites are a lithe close and not as private, but great for a night or two, to get clean and fill up water, etc.