Another point... Since soldiers were issued clothing and had the costs deducted from their pay, those who had uniform pieces left over from service in the Federal Army during the War, often used them in the field so as to preserve the newer clothing for garrison duty (parades, guard mount, inspections, etc.). Same thing with officers, pretty much.
A quartermaster sergeant might not have gone to the field much, except perhaps on a major expedition (Big Horn & Yellowstone, persuit of the Nez Perce, etc.), so might have stayed in better uniform. Still, if he had a lot of fatigue duty to supervise (unloading, storing supplies, etc.) he might have resorted to a less-than-brand-new uniform.
You sort of have to decide what you are portraying, and go with that as you can afford it. I personally think field or fatique duty uniforms are easier to formulate, as one only has to guard against "forward anachronisms" (i.e., uniforms that hadn't been adopted yet, rather than equipment that had been previously utilized.