Do the Monster Slapdash
Set them up where no one can see them. Then dress normally, act nice, and be "That Creepy Voyeur Guy Who Seemed So Normal."
Kludge (klooj, n.): a clumsy, inelegant, improvised solution to an engineering problem. Kludge-O-Ween (klooj-oh-ween, n.): a makeshift, half-assed solution to Halloween. When it's too late to worry about finding the perfect costume, it's time to realize that ANYTHING can be a costume.