No doubt you tested these for your own ground conditions and they must work but I have a suggestion or two for anybody else building a similar setup. We at AFS have found that a stand similar to yours only works if it has a third toe that goes straight back (instead of a driven into the ground anchor as it appears in the photo that that is the way yours are). The base resembles a chicken foot. We have found that the driven anchors only work good in certain soil conditions,too sandy and they shoot loose, to hard and you can't get them in the ground far enough.
Also I would make the front forks a little longer so you can tilt the uprights forward a bit (quit a bit actually) to absorb impact better. This way the targets stay lined up as set a lot better. Standing too straight up with driven anchors to pivot on, they turn easily and you are forever shutting down to re-aline targets. Poorly alined targets can cause unpredictable splash-back to neighboring stages.