In order to reduce the number of transmission bounces needed, if mouths are closed, set all of those interior parts to be completely (remember to zero out specular). For clothes, use the same setup as shown above, using the clothing's color map. Render with plenty of transmission samples and set transmission bounces high (32?) and the overall max bounces high (99?). The render engine will only use as many bounces as needed to complete a path from camera to light source.

Here's the ghost MAT set.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5