Gorgeous campground for those who enjoy rustic camping (no utilities). This place is extremely popular and reservations are not taken, so arrive early. It took us two tries before we landed a site here (Hurricane River is a good backup spot). The North County Trail passes right through this campsite; the only downside is, no dogs allowed on the trail (we were issued a warning).
Not sure if you can walk along all 12 miles, but you can go for the classic long walk on the beach here and even connect to the North Country Trail. Unfortunately you can’t reserve in advance so get there early afternoon so you can get a site along the dunes or beach or with shade (or by bathrooms, whatever your priorities are). No water, bring treatment or containers. I think the lakeside sites are few dollars more. We were lucky enough to be there during a meteor shower in spring when almost no one else was around. Not the best site if you’ve got bad knees or an accessibility need, as is true for pretty much any sandy MI campground.