Seriously, have you seen half of the bent cast, damn...
No, I haven't, that's the problem. I've seen Shinjiko, but from what I remember of your backstory for her I'm not sure I could do an awful lot with her.
The basic issue is that none of the female characters are of massive interest to me, and nor can I see any way to involve any BDSMy stuff. Further, I don't know much about how the genderswap changes them all. So, it's not easy for me to think of anything for this setting.