Hi. I've only just started using Daz this week and I haven't gotten around to using skin doctor so I'm not too sure if my advice would help, but I ran into a similar problem using the the new victoria 7 genitals and trying to get it to match the skin color on my Genesis 3 characters.
What I did was change the shaders for all 4 parts of the genitals from AoA_Subsurface to whichever one I was using for my character. The shader I use is Iray Uber, so I changed it to that one.
Again, I don't know if this will help, but I'll probably be playing with Skin Doctor later so I'll try to troubleshoot it then.