Stayed at Mackinaw Mill Creek, nice place. We were at the water and could look directly across the straits at the island. Ludington St Pk is on Lake Michigan. South and North Higgans St parks, On Higgans Lake, not Lake MI but rated one of the most beautiful lakes in the world, pretty tuff to get in there though, fills up early. Young St Pk at Lake Charlevoix, also a beautiful lake that is connected to Lake MI. Charlevoix is nice walking tourist town. St park at Burt Lake is also nice. Lake Mi is nice but there are so many nice parks on smaller lakes that you shouldn't rule them out.
Haven't been to Silver Lake St park in years. If it hasn't changed I would look for a private campground in that area. The state park roads are/were too small to take a decent size RV through.