Before 3-D targets became the rage, most archery clubs around here offered broadhead tournaments using cardboard silhouette targets hung from wires a few feet in front of sand bunkers. The arrow passes through the cardboard, the hole it leaves behind telling the shooter where he hit (and his score). Then, the hole is taped with masking tape from the back side of the target.
Pretty easy to string a couple of wires from posts on either side of your sand bunker and to construct your own cardboard silhouettes. And for practice, there's no need to tape the holes, but taping does extend the life of the target. Cardboard does increase feather wear, but they last a long time before the shafts need to be refletched. Have fun.