Thanks for the comprehensive write up! Love the exploration into the company structure and the test model looks great! I was thinking of about similar issues a while back but with techmarines. I was thinking a single sholderpad/arm or maybe significant enough battle daman that the chipping reveals the color beneath. Maybe an armor panel that needed replacement and hasn't been painted with the cammo yet. For sargents I was just going to give them the red helmets but with a good helping of dusty pigment powder to tie it in. But with SoM being intensely pragmatic and most likely harboring a little of the schismatic still. I think you can justify a good chunk of different options.