Making characters sever properly turned out to be more complicated than I originally guessed. There were many issues to consider at early stages of the character creation. We learned by trial and error to organize our material IDs in an efficient layout to reduce draw calls.
Basically, we had to build 2 versions of every character, one that had few materials and no severs, and one that had lots (24?) of severs and materials. After spending much time wrangling the various issues I wrote a design doc for a feature that would allow the build machine to do the bulk of the tedious copying and renaming of various materials, meshes, and their material IDs to create the cheap, non-severed model. This turned out wonderful and allowed tech artists to work on the severed mesh and the build machine created the cheap version.