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p.net has a few trip reports - http://www.paddling.net/places/MI/
Munising has an excellent campsite, there even is a motel "bay view/sunset view" or some such
Beaver is car accessible, you can put in there, follow the creek down to LS, and return.
Here is the link to maps - http://www.nps.gov/piro/planyourvisit/maps.htm
GPS coordinates - http://www.nps.gov/piro/planyourvisit/upload/GPSCoordinatesPIRO.pdf
You can guess which ones are kayak accessible.
You can camp on Grand Island as well
Here's the park website, link to the park map on the lefthand margin.
You can see the possible put-ins are Sand Point (easiest), Miner's Beach (longer carry) and Beaver Lake (long carry!). And you can see other campgrounds, including those available on Grand Island.
I have gotten there peak season but on a monday and have found open campsites at twelve mile beach. Kingston Lake campground is inland so sometimes they have spaces when the others don't.