How do I help my deaf ferret know when to stop playing?

I’ve got a 2lb 1 year old deaf boy who is sweet and plays very  gently with me. But I just brought home a second. She is half his size and also very sweet. They seem to like each other. They explore each others space with no problems, eat next to each other and she will invite him to play. The problem isn’t that after a few minutes they play get some rough and her Dooks turn into squeals, she will try to run away, but he doesn’t get the hint because he can’t hear her. I stop play when she is backing into corner a and twice she has pooped. But 10 min sleep later they are fine wandering around together and exploring again. 
How do I help her out and teach him when’s enough isn’t enough? I’d liketo house them together at some point, they snuggle up together outside the cage. But I’m afraid to leave the them together unattended until he can read her cues. 
Any ideas? He so much bigger than her, I don’t know if she could tell him off if she wanted to. 

Hello and Welcome to the forum! You could try time outs when he does that. Maybe 5 minutes. Or hold him up and in front of his face and say no. I realize he won’t hear but can understand. I did this with my deaf ferrets. You can also use Bitter Apple. Spray a little on the neck area of the smaller ferret. 

 
Fuzzbutts Rule!

Thanks for that suggestion! 
I’ve been trying time outs but I’m not sure he gets it. I’m also worried that it will develop a resentment in him of my gal. Like he will associate playing with her, and punishment and think SHE is the bad thing. Is that a thing with ferrets or not something I have to worry about. 
Does the butter apple also stop them from playing AT ALL or just stop bitting at each other necks? 

https://youtu.be/tQrNRhNGkb8

I’m also concerned that I can’t tell the difference between play and fight. I really think HE THINKs he’s playing but these are my first ferrets so I’m really not 100% sure. 
This is a link to a video of them playing and it’s gets pretty nasty. He just will NoT stop unless I pul him off. I’ve let it go on a bit longer a few times. No poop or blood but she’s definitly gets really upset.