>>314116First off my personal favorite. This is Mid-Central UP but worth the drive. There are a bunch of campgrounds in the Hiawatha National Forest along Highway 13. There is anything from full running water electric sites, to rustic dispersed camping. I grew up spending summers there and the fishing is/was great and you can find whatever level of roughing it you want. There are lots of trails and hiking options. If memory serves me right, there are even rustic sites on islands.
I almost forgot about Fayette. It's an old ghost town in a bay that was used for smelting ore back in the day. Gorgeous white cliffs in the bay on lake Michigan and some nice campgrounds close by.
If you are just looking for a closer RV Park style I would go with Kleinke or JW Wells in Menominee, but I'm a fishing fanatic so all of my camping requires water.