A few years ago I decided to make my own "decoy" of an angus cow. Made it out of that 1/2" foam sheets you find at Lowe's. Main reason, I was going to be hunting a ranch with lots of angus cattle.
I'd like to say it woked, but my shot went low.
But the really weird part was the reaction of the cattle! I didn't walk a 1/2 mile, stopping, spotting lopes, and moving in slowly. When I noticed a few angus coming towards me. Then a few more, and more, and more! Before I could get within' shooting distance of a nice buck, I had to have had at least 150 cows following me around!
So, yes, the decoy worked, but my cover wasn't the one I made, but the whole freakin' herd!
I would suggest you make it small enough and sturdy enough to easily carry and hold up in high wind. Put some kind of stakes on it so you can plant it in the ground for shooting and spotting. Put some kind of hole in it to shoot through and spot your quarry through.
But the main thing is to watch your back . . . if those Bison do to you what those cows did to me, you might be in some trouble.