Shoot Steel
Pair of self-locking 3/8-inch AR500 hangers that grip a standard 1.25 or 1.33 inch T-post under load, with no set screws or clamps to tighten.
A T-post costs a few dollars at any farm store and drives into the ground with a hand tool, which makes it the fastest target support there is. These hangers turn that post into a mount. Each one is cut from domestic 3/8-inch AR500 and shaped so the plate's own weight cants it against the post and locks it in place, with no set screw to strip and no clamp to lose. Lift the load and it slides to a new height. Use two so the plate hangs level, add chain or rubber straps and quick links, and the setup carries anything from an 8-inch 3/8-inch gong up to a 1/2-inch 12x20 silhouette. One number to respect: the maker sets a 50-yard minimum for the hanger system itself, which is a separate floor from the distance your cartridge and plate require, and the larger of the two wins.
Add the T-Post Gong Hanger Set to your build and see how it enhances your platform.