It's only a small part of the face, but the SSS-part can be seen in the light through the left (her right) nose hole wing (or whatever that's called), so it's there alright. I had to do this very subtly or it would have been too light. Decay depth is 0.017 I believe and density 2 with an unvaried medium reddish as color.
I believe the diffuse is also needed to give e.g. the lips its color. And I have added patches of dirt, skin variation, scratches and pimples, and such, and sometimes may even need body paint. Some procedural, some by image map. I also need bump maps for these low poly objects. I don't know if that really works now.
One can achieve a lot with just glass and roughness for variation (and maybe the skintone can be altered by using a darker reddish (blood) color), but I think there needs to be a way to add diffuse textures to the glass.
Also for things like icebergs; like (fake) rocks caught in/on the ice, strata lines (though the latter can probably be done through color input).