MILS Basic Track Modules
I think going to these three modules would let us cover all possible bases for track configurations. Instead of 3 ballast standards as we discussed, it simplifies down to 2 for maximum modularity. It's a mostly light grey mainline and mostly dark grey sidings and yards.
The leftmost module is a basic yard module. The middle module is a yard with mainline or siding with mainline module. The one on the right is a mainline module that can accept any MILS compatible terrain in the 16x32 green part.