I'm up for a winter hang! Just nail down the dates and location and I'll see if it works.
Regarding Sleeping Bear Dunes: This past August my buddy and I along with our daughters camped at White Pine Backcountry Campground. It's a easy 15-20 minute hike from the car and once your there, it's a quick walk through the dunes to the beach. Best swimming we've ever had with great waves! It's a fantastic location with a group fire pit, bear vault and pit toilet. No reservations are taken and in the summer the drive-in campgrounds fill up fast. I snowshoed there a couple years ago and really had a nice day of it. Pic attached...good hanging trees immediately past the bear vault closest to the lake. Note, when we met with the ranger to get our permits, they seemed confused about the hammock concept. They count a hammock as a tent, so we needed 2 sites for 6 people (2 tents and 2 hammocks). Best time to go is mid-week to avoid the crowd. If you're making the trip, might as well include a couple days at North or South Manitou Island!
That Pit Toilet leaves a lot to be desired. A few of us have camped at the White Pine site, very nice. We did a group hang on NMI a little over a year ago.
Its a proven fact that 78.4% of all statstics are made up on the spot.