When I was managing the Dugdemona range, east of Jonesboro, Louisiana, I built a gong holder for the regular folks to shoot at. It was a very heavy chunk of steel, a good foot or more in diameter. I used treated 4x4 posts/timbers to mount it on, at 100 yards. Sorry shooters, shot the 4x4 posts more often than they hit the gong with at least a foot and a half separating the gong from the timbers. The accuracy potential of the typical Louisiana deer hunter is really, really really scary. They could not hit water if they fell out of a boat.
Back to the point. As far as target holders, I go back to my silhouette swingers. Using a welded rod, forming a three sided box, it slips into couple pieces of angle iron with a tube welded. Chains or heavy straps hold the targets. Had the kids at the shop class at Quitman high school weld them up for me as a class training project fifteen years ago. As long as a fellow does not plaster the the steel rods, they last forever. They aren't pretty but as I said, been shooting at them for a decade and a half and they keep on hanging on. Pun intended.
I needed something easily movable and transportable. See first paragraph. they can't hit the but of a bull with a bass fiddle but they love to destroy targets with their magnum rifles at ranges far too close to be shooting rifles. I think they refer to it as a mark of manhood. (destroying stuff that isn't doing them any harm). Damn near the only thing about Louisiana that I don't like.
I will try to get pictures to add to this post tomorrow.