I've been there several times.  This campground has been around a long time and is well known by motorcyclists in Michigan.  It's located behind their motorcycle repair shop.  It's not a fancy campground, but it is a bargain at $10.  The northern loop has electric outlets.  The southern loop is rustic camping (groups usually camp there).  Restrooms, showers and a pavilion.  Pay the $10 at their shop.  If the shop is closed either someone will come around or you can settle up in the morning.  Firewood available on site.  Village is 1.5 miles away to get supplies.

I tent camped there July 2023 and the site was $20.  The campground host was a very nice and helpful lady.  There are electric at the sites and there were water supply spigots throughout the park.  They do have free wifi, but it is very weak by the river sites.  It is strongest near where the camp host is since the antenna is behind her camper.  There was an old wifi access point plugged into my site's electrical outlet, but it was inoperative.  Cell signal is good there though so it wasn't a big deal to me.  Since I was tent camping I cannot attest to what size RVs and electrical amperage they have.  The showers and rest rooms are locked at night.  Just ask the campground host and she will lend you a key for the night.  In addition to the main camping loop, there are about 12 river RV sites near the fairgrounds.  It was fairly quiet being a week day.  Just leave your trash in a bag near the lane and she will pick it up when she makes her rounds in her golf cart.  A grocery store and a convenience store are across the road.    You can book a site online via the village's website at https://marionmichigan.org/campground/  According to a google search the phone number is  231-667-0100.  If that number is not valid the village office's phone number is 231-743-6801