We winter camp, but won't un-winterize the water lines till temps stay above 32 day and night. We basically dry camp. No water in the toilet, shower, or sinks. Nothing down the drains, and we use a port-a-potty and dump the contents every day into the campground pit-toilet. Bring water with is in jugs as the campground water (in Indiana) is turned off till April 1.
Keep warm with gas and electric space heaters (state parks in Indiana keep the electricity on), and just enjoy ourselves.
Problem with Illinois, just like Indiana, especially in January, it might be 5 degrees one day, and 50 the next and then go back to 5 the next.
If you de-winterize anticipating the 50 degree weather this week-end, then be prepared to winterize again, because Old Man Winter can still hang around until the end of March if he really wants to.
