My primary goal is merely to provide a visual distinction for our play group's upcoming campaign game. We have settled on a colored bar on the bottom bevel for formations and a transparent mask for inactivity. And if either proves unsatisfactory, improving is rather simple.
edit: We will have the formation and inactivity as open information, which keeps things simple.
My secondary goal is to learn a bit about how Vassal works - what simple things can and can not be done with it.
Unfortunanely duplicate traits can not be removed from the extension's prototypes. I already tested it when I was experimenting with "PG Unit" and verified it now. If I remove "Cycle Hidden" trait from "Axis Unit", it is no longer available in the context menu and the shortcut key no longer works. This creates a sort of merge conflict, should those prototypes later be modified in a base module update.
So this probably works mostly due to luck. We will play with it once, when we actually get to first Combat Phase. If no problems appear, I will then email the extension to you.