I worked in a chain of small-town fast food restaurants that served a hot fried chicken. There was no sauce. Our restaurant actually halfed the amount of rub we used because otherwise, the chicken was "too hot" for the customers. This was in no way meant to be "buffalo wings", just your basic "fried chicken". We used a dry seasoning mix, quite a reddish color, both cayenne and paprika (and other spices as well). The chicken came in pre-cut and we would clean the pieces of extra fat and such and rinse the pieces. We then tossed two complete birds in a big s/s bowl, tossed with this dry spice mix and put back in their bags in the cooler for use the next day. The next day was a dump in flour (seasoned, but with S&P, not an overly spicy coating), dunked in ice water quickly, drained and tossed back in the flour. 15 mins in 325-350 degree oil for two complete birds. The seasoning mix would burn the underside of the fingernails and if there was a cut, it hurt badly...
On breasts, obviously, once you got past the outer flesh, the heat was not in the inner flesh, but the heat would stick with you. I'm wondering if instead of a wet marinade, you used a dry spice mix, you might achieve the results being desired. Also, even if you pulled off the breading, you could see some spices, but not an "obvious" layer of seasoning. While I refer to it as a dry spice mix, the chicken was wet from the water, so the spice mix was wet, but only a surface wetness, not a liquid marinade but also not a classic "dry" rub.