Hi all. Hope you guys can help me figure out proper placement of my poop boards. My roosts sit at 3 feet high and 15 inches from the wall. Based on where the chickens vent is while sitting on a roost (I have large breed birds: Speckled Sussex), how wide does the poop board need to be to successfully do it's job and catch all the poop? I've got 15" wide boot trays, so if I place them centered under the roost--there will be just 7.5 inches on each side regardless of which direction the chickens happen to be facing when sitting on the roost. Is that sufficient? Also, what is the proper distance for the poop boards to be under the roost? Is 12" below the roost sufficient? Too much? Too little? Thank you!