So i was thinking, there are a few black themed bases around and a couple ones based on white. Specifically, Jet, Obsidian etc AND Cimmerian (which i wanted to use as to make it relevant and not a one time novelty) crossed with Albino, irrelevant of weather and other criteria. It can be based on Black Dark Solid Genetics if applicable!
Example of factor bases:

The combo base:

And with subtle standard markings (i cant place them properly but you get the gist of it)

It can work with Piebalds as well as Patches to a lesser extend!