I've been using black garbage bags in winter,,, white in summer for LR shooting.
Fill with air and watch it deflate when it gets tagged.
I set them at close range distances at 800 to 1700 meters for practic since they are close to Deer size body girth...
Frugal to shoot and a person can flatten out lots of them in the day,,, most are reusable so long as a person brings the ductape. LOL.
Place them in many configurations like stacking,,, spread-out or single format at each shooters choosing.
Normally I use the medium size garbage bags since I get 100 of them for $3.65 a box.
Deflation is a good thing you know. Ha
Good luck on the target acquisition all,,, good times happen to those that go after it.