There is a private golf club with a hill made for sledding right off the main road in town with an ample parking field. While they have never officially "invited" the public to sled on their hill, it has been the de-facto "go-to" sledding hill after after every snow fall. Their parking lot can fill with literally 100 cars with many more walkers arriving.
Does the club have any liability for negligence if a child gets injured due to unsafe conditions? Perhaps too many people sledding at a time to be safe or icy walk-ways on the way to the top of the hill?
Again, I am not sure if the sledders are considered trespassers or are even technically welcome. After decades, it is inconceivable to think the club doesn't know the popularity of the hill and has done nothing to dissuade its use.