Normally I hate mixing paints. It's a huge pain to try to get consistent colors, and if you can't get everything done in the time your paint dries on the palette you're making a new batch. But since the store isn't open and I wanted to see how this would look, I decided to try mixing Feldgrau with Orkhide Shade, the bluish-green I'm using for the collars and shoulder loops, to try to approximate the feldgrau green-grey of the early war. I then added some Grey-Green 886 to the mix for a highlight.
I think it came out pretty good, and I like the overall effect. I'll see how closely it resembles the actual German Uniform color, and I'll still get the German Uniform paint, but it's good to know the look will work.