I suggest that you try some research by using RV Park Reviews.com (click below). Select a Michigan city where you might go and see if there are any campgrounds in that area. You can then go to the campground website, if available, to check on amenities available. There are also customer ratings for the various campgrounds.
http://rvparkreviews.com/regions/Michigan/Here's a FHU campground about 45 miles west of Marquette, Michigamme Shores CG. It's along M-28/US-41 on Lake Michigamme, a very large inland lake.
http://rvparkreviews.com/regions/Michigan/Champion.htmlCheck out these campgrounds in the Ontonagon area. The Porcupine Mountains State Park is just south of Ontonagon and is a great place for hiking. We stayed at the Ontonagon Township Park, just north of downtown Ontonagon. It has water & electric, but I don't think it takes reservations. It's a nice campground right on the beach.
http://rvparkreviews.com/regions/Michigan/Ontonagon.htmlAnother campground we liked which is right on Lake Superior in Grand Marais (between Munising & Sault Ste Marie) is Woodland Park. Again, water & electric, but it's a nice park with grassy sites. You can walk into the downtown area a couple of blocks away. Check out The Lake Superior Brewing Co.
http://rvparkreviews.com/regions/Michigan/Grand_Marais.htmlAlmost forgot to include Copper Harbor.
http://rvparkreviews.com/regions/Michigan/Copper_Harbor.html