We had two BP pitchers that used a mat to toss BP. When setting up the protective screen in front of the regular mound, what we didn’t want was to deteriorate the front of the mound with the constant landing - regardless how short that landing was, of the pitchers. Granted, BP pitchers usually don’t stride, they kind of short-step, and a quick snap-throw to the batters. Nevertheless, those repeated short-jab steps did take a toll on the surface condition of the mound.
The mat that put down was nothing more then a cheap rug, kind of.(nothing but the best with these guys.) In reality, it was a long hallway runner that stretched from the rubber to about ten (10) feet down the front of the mound. The benefit of which saved the expensive mound mix ( the cost to our club of resurfacing) and a darn good stable surface to land on.
So… you might want to try and purchase a cheap hallway runner rug, anchor it somehow to this artificial mound, and see how it works out for you.
If you have a condition where this equipment isn’t yours, but property of somebody else, you might want to talk to those people - person, about making this thing a lot safer and workable for everybody concerned. So what if the rug has blue and pink balloons on it - looking like a loaf of Wonder Bread … so what? Ours did… kind of lighten things up a bit in the process.