Most of the campgrounds that far north are closed for the winter. You might consider jumping over to Jackson Center, and overnight at the Terraport on the Airstream Factory grounds.
As far as Flying J's and Wal-Marts are concerned, we overnight in their parking lots on a regular basis and have for quite a few years. We have always felt safe there.
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2011 Silverado 3500 (Fred) with Outfitter Truck Camper (Ethel)