I made a self supporting stand of out 3/4 PVC pipe. It will stand in the wind, and hold a nice chunk of cardboard. Plus it comes apart for easy transport.
The one mistake I made was I had it too close to the steel bullet trap. As you can see it got hit by some ricochet bullets. But a little duct tape and it is all back and running. You can make them up to four feet tall. And they stand real well on almost any ground.