Chastity and orgasm denial discussion

To make sure this is understood correctly, I’ll begin by stating the goal my Mistress Wife and I are aiming for… “The objective is to permanently damage the penis in a way that will make it more difficult for me to have an orgasm and also make it far less pleasurable if I do have one.” Now there are obviously some extreme ways to accomplish this task. For example, just cut the damn thing off. But we don’t want to resort to anything that severe. She also doesn’t want any piercings, and prefers not a lot of blood in the process. Currently we are giving it frequent scrub downs with some very rough sandpaper - focusing especially on the head. Obviously there is some bleeding, but not too bad. I think I can tell my cock starting to lose a bit of sensation already; but I’m wondering if any of you have any other ideas?