Boots on fence posts and shoes strung over a wire reminded me of an older but similar ritual.
Back in the 19th Century when Bangor, Maine was the "lumber capital of the world" massive spring river drives were used to move the logs cut over the winter to the mills on the Penobscot River in Bangor.
River drivers jumped, walked and hopped across the logs using their peavey to clear jams and sort logs into various rafts. If they fell in and drowned, their calk boots were hung from a tree on the riverbank where their body was found. (Calk boot is Downeast Maine speak for "cork" boot, a logger's boot with studded soles.)
Given that the river drivers were well known for their drunken and licentious ways, it is doubtful that their souls are resting easy somewhere--if one accepts such a proposition. Perhaps boots oddly and mysteriously placed on fence posts are the actions of tormented river driver shades.
I think it is best to give those boots a wide berth as they are likely haunted. If you must get close, first toss a black cat over the fence at midnight. If the cat does not disappear as it passes over a boot on the fence ... well you are on your own--unless:
For $19.95 plus shipping and handling, I can arrange the procurement of genuine Penobscot River anti-haunt water. VISA and M/C accepted.