not to sound like a jerk here, BUT if you need your targets to be reflective, , how do you plan on shooting wild game> as there not
and I gather you also nee to be precise on aiming at wild life as you would targets of other materials!
that said,
couldn;t you maybe just use a small light to help illuminate a target so you can see better, to dial in the scope?
rather than trying to make some targets out of reflective materials
some of them better end solar powered lawn lights(many do 200-250+ lumen's, they will be easy to place at distance and help add some light to a target and be safe to do so, ?
fast and easy too I would think!