I got back around to this substance and getting it stable in Unreal. Came out running pretty smoothly in real time and even made it all work with just one slider. Though there are extra options for the rocks, debris, color and some extra wet spots.
You can get the SBSAR on Gumroad here: https://gumroad.com/l/HaIwb
And see my whole set of Substances here: https://gumroad.com/_dc_