Another one is the National Campground at Bowman Bridge west of Baldwin. It's on the Pere Marquette river and is a major stopping area for the local canoe liveries. They can pick you up there, plop you in the river in a canoe, and you can finish right at the campground.
Right across the street is the Big O loop. Just a few miles up is the lot for Little O, Manistee and Lincoln Hills.
$12/nigt, no power, water is there but you have to haul it. Paved sights, or tent sites also. There are also large group sites.
My wife and I go here often, it's not used much.