I am a slave. What I mean is that I am in a fully committed long term (life long, I pray) relationship. I am female and my master is male. He has decided that he would like to train me to better receive anal intercourse, to that end he is considering putting me in chastity for what may be an extended period of time, with the intent that I should receive sexual satisfaction only form anal use. This is a bit scary, but it is a huge turn on too, so I want to tyy it, and at least see how long I can go, but I'm a little incertain on some things. There is a lot of good stuff in other threads about hygiene and the like, which I confess is a little intimidating in itself but... okay, I'm ready. But the big question that I had the most trouble answering is about actual anal sex...
My first question is that my sire has a rather ample cock. Not porn star huge or anything, but not small. (He is larger than any other man I've ever been with, but nothing like me most of the cocks one sees in internet porn... Maybe 7-8" and the diameter of a half dollar coin?) What sort of belt would allow him to use me easily and pleasurably (I mean, his pleasure, though I would be very happy for it to be pleasurable for me too!) I kind of like some of the MySteel ones with an anal ring (though I think neither he nor I would he happy with the big locks flopping around), but is it big enough? How about chains? They seem to me like they would be hard to keep as clean as I would want for long term wear... But?
Anyone who has experience with this situation, I would really love the advice. If I can find the right belt, he will buy it for me. But if he is unsatisfied with the outcome... Well, I don't think either of us will be very happy about that, if you know what I mean.

Thanks in advance.
-WB