I’m somewhat confused by the terminology you’re using: sexual sensations are physical, erotic sensations are psychical.
You can have erotic sensations without any sexual stimulation (like watching someone in erotic clothing), and vice versa, have sexual sensations and functioning without erotic thoughts (there are means of purely electrical orgasm induction).
What you describe as physical means of reducing stimulation, do not necessarily eliminate erotic ideation, so I think you should first very carefully establish whether it’s the physical or the mental sensations that are at the root of your trouble.
so my thinking is, if I didn’t have nipples or a penis, or scrotal skin, then that should fix things; can’t stimulate what isn’t there, right?
That’s… not exactly correct. Our minds have a “body map” that reflects the stimulation of different parts (and cancel stimulation when two parts come in contact, which is why we usually react more to someone else’s touch, than to our own armpits, arms or legs rubbing against each other all the time)… but when a part is missing, you can get a perception of over-stimulation, with all kinds of sensations:
Keep in mind that if you were to get that, you would lose any physical means of controlling which sensations you perceive, which could be even worse than the current situation.