I was able to put some time into Dixie's portrait today finishing up the ears. I decided to go with my instincts and make the farthest ear a bit smaller to emphasize depth and made sure the darkest value was a "hair" lighter than in the other ear. This keeps me from contradicting myself and sustaining the illusion.
Also, it's a good idea to get some warmth ie. reds and oranges into the ears. This will represent the translucency of the ear with light passing through illuminating it with the higher chroma red showing up visually. Furthermore, in the photo provided by the client, this area was very dark. This is common in photos. I needed to rely on what I know about this particular situation and ignore the value structure presented to me in the photo to add life and the sense of light I'm after.