Those mats look like a great product. What we did back in the late 50’s and 60’s was use bricks on both the mounds and batter’s boxes. In fact, we just set up a mound with bricks last year and it’s held up magnificently.
One of the biggest mistakes is filling in the holes and then trying to pack it. It will pack, but not very tightly. In order to do get it to pack well, the soil has to be moistened.