Typically we solve a character in passes. So we will do a muscle pass and fascia pass and skin pass. There are variations on that but generally that's it.
For the muscle pass we have skeleton geo we make a zBone and use that to drive the muscles which are zTissues. That gets baked out so we will have a bake of the muscles.
For a fascia you can combine the muscle bake and and attach a fascia mesh as zTissue to the muscle bake as zBone. Attaching could be a combination of sliding and fixed attachments depending. If you have collision on you will get a better result as the internal muscle that may come to surface will be accounted for. In this instance the fascia gets baked out. Cloth is still experimental but we have had good results using cloth for a fascia.
For a skin you can take the fascia bake and make it a zBone. The skin as a zTissue and attach it to the fascia. At this point you probably want to use mostly sliding attachments and some fixed to pin areas.
If the fascia and skin are water tight meshes for these purposes you will want to turn off fill interior on the zTet node.
Will will have examples of some basic setups at some point so hopefully that will make things clearer.