This is interesting to me. I'm still trying to learn how to crappie fish, but I've caught many, many stripers jigging. My go-to rigging method is exactly what you show, but with a 7" Bass Assassin. Basically, it looks like a giant version of your exact setup.
My reason for fishing upside down is not color, but because if I rig with the hook coming out of the slit on the bottom of the lure, it has a lot more action and becomes a swimbait instead of a stickbait in action. But your logic on an upside down baitfish is very interesting and may explain a lot!
Here are a couple of pics of my nephews fishing "the upside down". The lures are in their mouth, but you can't see them well.:
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