I was thinking of something more versatile that would allow the creation of subsets (e.g., left belt 1, left belt 2, right belt 1, etc.) that can be combined to create other subsets (belt 1, belt 2, etc.) that, in turn, could be combined with various backpack and headgear templates to create complete equipment templates. Creating an easy-to-use GUI for that would require careful thought and might be onerous to code.
All respect, how often do you envision using such a detailed procedure, and what for?
As the game is now, I personally have pretty much a handful of "templates": sniper, assault, heavy, grenadier. With, say, three variations of each, I suspect I could cover 99% of the missions likely to ever occur in this game, and that's still only 12 templates, very easily created and managed. Heck, I could probably easily manage most of the game with those four.
For the other possible "special" missions, I imagine first creating and then mixing & matching the detailed templates you describe would require equal effort to just doing it by hand like in the current system, as a little customization before missions is fine even now - it's the constant loading of the same equipment on all soldiers that really gets old for me.
I'm thinking the returns beyond what I described would very quickly diminish, while in my experience practically everybody would love to be rid of the micromanaging that's traditionally plagued this aspect of the entire genre.
BTW, IIRC Jagged Alliance 2 was modded to do in essence something similar to what you describe and while it had advantages and tinkering with my paper doll loadouts is often fun, I really think a simpler system would fit the flow of this game better.