Hey, thanks for the feedback.
You can hack together a collision offset by doing the following steps:
- Duplicate the muscle that you want to have offset
- Sculpt the duplicate to have an offset (you could use the sculpt geo tool in maya and just flood along the normal)
- Transfer the muscle setup to the duplicate. (ZAT menu)
- Embed your original muscle inside the duplicate. (Ziva > Add Tissue Property > Embedded Mesh)
This won't be separable like you mentioned, but it's something if you're in a pinch.
Paintable collisions has been raised internally, there's a ticket for it but afaik isn't bound to a release yet.