Kelleytoons (8/8/2020)
Cloaks like this will ALWAYS be an issue - but you can clean it up somewhat (just don't expect it to behave as a real cloak).
First of all, reweight it as a cloak or cape. That will help a lot. Then create a physics weight map for it and experiment with ONLY having it attached at the shoulders/arms, with the rest of it all white.
But let me say again this will be a challenge. You are unlikely to get it working the way you think it should (which is why I always ask folks to ask me first before they buy any Daz item and I will tell/show them how well it will work for CC3).
What do you think it would take for a true ready-for-wear clothing apparatus, as would be wanted? Maybe would have to be some particle, like how UE4 achieves Groom hair through particles.