I get where you're coming from but anal doesn't usually feel like a very submissive act for me- probably because I experience it as pleasure rather than pain. I feel like A2M is more of a submissive act for me than anal penetration itself, although the two often go hand in hand. For me the most private would be parts of my mind rather than my physical being.
Which is why the A2M is so popular.
I learned how to gape from doing webcam modeling, so it's probably also that a lot of my anal action for camera has been in my control as well. It must feel very good for a man to fuck a woman's holes so much that you can see them staying open in lieu of the penetration, so I can see how to a man the gape is very sub.
I believe that the keyword here is control. A man who gapes an anus has to some extent control over it, or that it at least what he feels as he looks into it. Same thing with the A2M: the man who puts his cock into a woman's mouth and has her clean it even though she does not like to to so is certainly in control over the woman. Same thing with the webcam: he requests it and you perform. He is in control and you anus opens on command. If you performed for me I would instruct you in detail what to do. First, how to stand, how to spread your ass, and how and when to contract your anus in close-up. Then, when to lower your anus over the dildo, when to stop, when to go back up. And finally when and how to move things and fingers between your holes.
So you see, when we want to fuck you in the ass, what we really that mind of yours we want to fuck.
As a man, you want women to submit to you because that demonstrates that you have value to them. They will do unpleasant things just to demonstrate their submission and the value they place in the man. It's very much to put the money where the mouth is, so to speak. And this is the fantasy, or in some cases reality, that porn plays into. Unfortunately simply paying for the pleasure does not work. I am sure that I could get some poor camgirl in Thailand do almost everything to please my credit card, but whatever she did it would simply be a coincidence of development and trade economics. It would have very little to do with me as a person, and that is why Thai camgirls are of very little interest to me.
Conversely, the reason women tend to find the same sexual scenarios interesting---just look at any site dedicated to erotica---is that women simply desire the other side of the coin: the man of such quality for whom they would actually endure all that pain and humiliation. Or just extra work. E.g. when I instruct a woman to keep her anus ready for anal sex and then, when I bend her over a bench, find a butt plug in her and that an enema has been administered. That adds value the the following for both of us.
I have some bdsm stuff in a list that I will post soon and more coming up
Just remember that for it to really work it has to be a bit humiliating. But still, as a part of the paying audience, you only get half the fun if even that.
A real cane will always leave more of an impression than a velvet whip or whatever.