After completing the Adventure Lab on your smartphone app, you will have found the clues for the final bonus mystery cache. Container is a small lok-n-lok with some swag items, travel bugs, and for the lucky FTF - an unactivated Berkshire Geobash geocoin.
There is room to pull off the road but in winter it may not be plowed. The cache should be winter-friendly but if there is much snow you might have to walk through it.
Please put the container back the way you found it.