Dang, I really thought that would work. But thanks for the suggestion!
It actually produces the same result if you turn off pin group, compared to just cloth sim parented to the base mesh.
I’ve been faffing around with hook modifiers for the last while to no avail either. Parenting hooks to bones doesn’t seem to do anything, I also tried hooking to empties that were parented to the armature, etc.
It’s really bugging me that I can’t remember how I did this before.