Many of the rest stops have been closed in years past, including Ludington, but now, they will mostly all be open. I know that Ludington's has a steep incline to enter into, and that is not that steep that it can't be plowed and salted, like all streets. So again, WHY LUDINGTON?

Here's the official why from WZZM you may notice the other three are all geographically close too, in Mackinaw and Cheboygan counties:  "The Michigan Department of Transportation (MDOT) says it will keep nearly all of the state's rest areas open this coming winter.
According to a news release, only five of the 78 rest areas in the state will close for a 20-week between between Dec. 5 and April 25, 2018. These specific closures are due to lack of use during the winter months and safety concerns, such as steep entrance and exit drives and potentially slippery conditions on stairways between the parking lots and buildings.
The following five rest areas will close Dec. 5 and reopen in April:
St. Ignace Rest Area on southbound I-75 in Mackinac County
Ludington Rest Area on northbound US-31 in Mason County
Topinabee Rest Area on northbound I-75 in Cheboygan County
Hebron Rest Area on southbound I-75 in Cheboygan County
Hart Rest Area on southbound US-31 in Oceana County
These rest areas will have "Closed Until Spring" signs posted, and will have the mileage to the next open rest area listed,"

... which will be quite a distance for these remote areas.  I appreciate the cost cutting efforts, but it does seem odd that other remoter curvy and hilly rest areas remain open while these don't.  

So, if you're traveling North, you can go at Muskegon, and you better be able to hold it until you get home, or at the airport Shell, say the MCSO. Great deal.