if it is as thick as you say....
just 1 side of a blind, a piece of plywood...cammo painted with real stuff from the area stapled to it.
.since ya know where they are comin from, you are in cammo behind this board that has a shooting hole through it..you can leave it there all the time, and chances are noone will see it. if they do steal it, it was just a piece of plywood..put a couple handles on it. and a stck will hold it up