Hello Nasicus,
I use normal type rack systems for my hogs. I only worry about substrate is when it comes to nesting. But to be quite honest, my nesting is not all that deep. Between 5 and 6 inches. I would call my nesting technique "full cage nesting". From what I can tell, it is deep enough and all I am able to offer at this time. I am more worried about the humidity, temperature, and security options than I am with the actual depth of the substrate.

While my technique has worked well, in some cases, wonders, for me and others who adopted it, there is always room for improvement.