That should be a no brainer.  I have done that many times with kgirls.  

I thought you were going to ask for anal or mfm or video.

Just ask

It's not really a big deal imo. I had some kgirls do this on their own accord, especially a few times I went soft during a sesh.

 
There are some kgirls, not that many but still not like a dozen,  
who will happily flick their clit while you're fucking them. Doesn't quite count as masturbation but I always thought that's pretty hot because she is trying to get off as opposed to just lie down and take it (which imo is kinda boring)

They are, IME, pretty open!
Whether they've initiated it, or it just happened or a transition during the session!
You've been around a while, surprised you asked this.

Spicing things up can be a fun change. Ive had girls drool down the center of their cleavage while sucking their tits. That was pretty hot. One time I even asked an ATF regular if she would pee on my cock and stomach. She was actually pretty into it and it was quite fun.

light to moderate BDSM.   However, they do not like to be dependent on a customer to remove the restraints by the end of the session, since, as well all know, Kgirls work on a strict schedule.   The best luck I have had training Kgirls to be subs is to take this kind of play outside the incall.  It takes an extraordinary amount of trust, but if she has been a regular for at least six months, and expresses an interest in exploring BDSM.  My suggestion is initially, you can so something simple, like the Velcro handcuffs and a blindfold, which she can remover herself if needed, and then if she was into it, suggest going out to your place (not recommended for married mongers - Lol), or a hotel room for a longer session that can be more involved and intricate.  

 
I also suggest that YOU have a couple of sessions first with a real Domme so that you understand the finer points between sensual domination, which is what most Kgirls are looking for, and the pain/pleasure threshold,  which can send a session South very fast if you inadvertently go too far with a newbie sub.  Ask your Domme questions about reading reactions and knowing when to go a little further, or calling it a day at some point.  A two-to-three-hour outside session allows her to explore her fantasies without worrying about running overtime or having her roommate become suspicious about what is going on in the next room.  This is not something every Kgirl wants to do, so you have to determine if they are just playing to YOUR interest in being the Dominant, or whether they have a real fantasy about being a sub, in which case they will be much more enthusiastic about learning.  If you have specific questions, I'm open to PM's about this topic.  I have found REAL interest among Kgirls to be rare, but rewarding if they are really into it once they get a sample.