Advice on penis crushing/torture

I’ve recently had my wife start squeezing my dick as hard as she can during sex. She’s been quite into it as she gave me a long session the other day of squeezing while sucking me off. She did something with her mouth also that teased my sensitive head. It was absolutely amazing!

I brought up to her that I would be interested in her stepping on and torturing my dick. She is open and willing to try. Her main reservation is pain for me, which I have felt none of so far. I don’t think she could really hurt me with the stuff I’m asking for. I’ve checked CBT sites and the subreddits but I mostly find stuff focusing on the balls. I’m not into ball play.

My question is how much crushing can a penis take? Is it just a pain threshold thing or something else? Any advice on penis crushing or torturing a penis is appreciated.