Hi, late to the game, but I know what works for ground cover. I use
dried native clay or dirt, broken up finely. If possibly, use an old coffee strainer to get the larger particles out. I paint the area with scenic cement first then sprinkle the dirt on using the strainer to alleviate clumps, then affix the cover with a fine mist. Areas of Woodland Scenics fine ground covers or small clumps of grass can be scattered in lower traffic areas.
Here is an example of the native soil used as ground cover:
View attachment 121366
You can dry the dirt/soil in an old pan on the stovetop, watching it and stirring occasionally. Let it cool.
Hope this helps--Dave