Not a lot

The player can encounter members of the Ku Klux Klan on three occasions. In these three encounters, the Klan is portrayed as comically incompetent and hateful racists.

Primarily found in Lemoyne.

The player has the option of killing Klansmen in all three encounters for positive honor, or observing the encounters and not intervening.

There is also the Racist in Saint Dennis who you can off without consequence.

ⓘ 𝘛𝘩𝘪𝘴 𝘶𝘴𝘦𝘳 𝘪𝘴 𝘴𝘶𝘴𝘱𝘦𝘤𝘵𝘦𝘥 𝘰𝘧 𝘣𝘦𝘪𝘯𝘨 𝘢 𝘤𝘢𝘵. 𝘗𝘭𝘦𝘢𝘴𝘦 𝘳𝘦𝘱𝘰𝘳𝘵 𝘢𝘯𝘺 𝘴𝘶𝘴𝘱𝘪𝘤𝘪𝘰𝘶𝘴 𝘣𝘦𝘩𝘢𝘷𝘪𝘰𝘳.

Not sure on the total, I think they continue to spawn. I know I’ve come across them randomly between missions. Like one time it was night and I saw a burning cross in the distance, so I snuck up on them and circled them to find a good angle to quick draw on their asses