Might be your saddle too. Some folks have very sensitive butts. I can ride just about any saddle. Might change my mind if I started riding centuries two or three times a week. But I just ride whatever saddle came with the bikes.

I wear these on every ride longer than the two mile round trip for groceries: Champion tech fabric long leg boxer/briefs. Good stuff. I wear 'em under baggies for casual rides and under my tight padded shorts on some road bike rides, especially on windy days when I don't want my baggy shorts flapping around.

No problems. The fabric wicks sweat away and air dries quickly as I ride. Basically the same fabric good cycling apparel is already made from. It's ultra thin, skin tight, doesn't bunch up, wrinkle or chafe. More comfortable for me than padded shorts alone. But the conventional wisdom says no underwear with padded shorts.

I know some folks need creams and butt butter with padded shorts. I don't now, although I did use creams with the soft chamois leather pads on merino wool shorts 30something years ago. That was mostly to keep the thin chamois leather soft and pliable.