I was at Oval Beach on a recent Saturday this summer and enjoyed a beautiful, sunny and warm, day at the beach.  I highly recommend it as a thong friendly atmosphere on one of the most beautiful beaches along Lake Michigan.  The only concern generally is the biting flies, and most days they are not a big problem.  There's nothing more refreshing and exhilarating for summer beach experiences in the Midwest than the Lake Michigan shoreline, with its clean fresh waters and pristine beaches.

There is a trust that apparently has funded the acquisition of private land to the north side of the public beach along the parking lot, with one privately owned parcel still holding out.  This has opened up this pristine grassland and dune area and the beach along it to more general public use, and makes for wide open areas along this stretch for unhampered sunbathing.  I would not hesitate to discretely lay out nude there on a warm weekday.  On weekends there are too many walkers going to the boat inlet north.
I brought several Skinz and Muscleskins suits and was planning on laying out with a husband/wife there when things got too crowded, so I headed 150 yards further north to a more quiet stretch of beach.  I was in and out of the water and laying out 30 feet up from the shoreline with no problems.  Several larger boats were anchored offshore with some inflatables bringing the owners and guests in.  Around 4 PM or so when things got quieter a m/f couple was beginning to put on a show for me from their foredeck just offshore when a smaller boat pulled up with adults and kids onboard, unaware that they were crashing the party!
There was one young exhibitionist who gave many an eyeful...a guy around 19 to 22 years of age, of slight build, who was wearing a minimal muscleskins suit, roomy pouch but not quite a pistol.  He was running and walking the beach on occasion in this (enjoying his bounce, shall we say) and laying out flat on his back with two guy friends in boxers and a gal in a near thong.  Quite uninhibited, good for him.
I had been going to Saugatuck State Park beach in recent years, which is very nice, long and expansive but requires a 15 minute walk to the beach area.  I'll plan on returning to Oval as soon as possible.
 

There are a lot of walking trails back in the dunes.  I didn't explore too much bit I did notice a number of guys coming out of the dunes down to the beach.