Rob, just an FYI if you own the DC Body Kit morphs or Blackhearted Femme Fatale morphs, they both come with 2 donor kits already. A long skirt and pants to the toes.

Since they are Hi Res, they will copy over the rigging and morphs much more efficiently and cleanly.

Also, keep in mind in weight map rigging, separate ghost bones are no longer necessary. A properly rigged weight mapped skirt will follow the pose all the way to the floor. You can move the thigh and shin bones as if they were ghost bones.

This pose is done with a properly rigged WM skirt and not simmed in the cloth room

However, no matter what mesh you are using a long skirt in a seated position will always look better and fall more naturally by simming the hip in the cloth room.