I used to do 25+ mile rides on the regular with 50+ mile and even a few 80+ mile rides in there too. Never did a full Century ride yet, but it's still on my list.
Bike shorts and vaseline. Vaseline is your friend. And it still hurts. Also will want to shave your taint and anything else hairy back there. Inside the butt cheeks too. I had a colonoscopy and the doc was asking me about being hairy all over but a totally clean shaven backside. Quite the awkward convo.
There was a razor in my shower you did not want to use.
I know I did the laughing emoji, but I'm serious.
Also: I am not the only one.
https://www.bikeforums.net/fifty-plus-50/730705-i-shaved-my-butt.htmlAlso, if you want to get really fancy for the non-greasy option: