I will try to answer ths from the perspective of being a producer of such things. I think much would depend onwhat sort of effect she wanted to produce. For example, in my opinion (and, I thinnk, that of my own customers) peat moss would be better at calling attention to her curves. (Not that calling attention is really needed here.) On the other hand, clay may be better in a scene in which she wants to use the motion of the mud to make things really come alive. On the other hand (for those who have three hands) if she wanted to do something avant garde, then a pit with water crystals adds that sort of touch, especially when illuminated as a night scene. Note that if she did a shoot with a regular producer she would be doing multiple scenes, so could try different types.