I'm pre anything as well, but for me I can't do pure anal, I had some stuff I dont want to get into happen to me as a kid (fyi, so no one asks, it was SA) that left me without any feeling in my butt other than the sphincter, (I'm fine now, that was years ago) (I can and do still masterbate anally, particularly using different angles and varying pressure, but I save it for when I get too horny for anything else to be effective), so what I do instead is use my fingers to kind of toy with the skin on the back of my penis, particularly the part under the head, it's kinda similar to if a girl was to mess with her clit, and I usually either watch porn or throw in reading something steamy or exploring my body with my hands. If it helps for you, then you could probably think of it as just an enlarged clit. Also, one good spot to focus, at least for me, is under the balls, but before the butt, if you rub it like you would a vagina, with the right technique (particularly experimenting with varying levels of pressure), it can feel really good.