The Black Klansman (1966)
Starring Richard Gilden, Max Julien, James McEachin, Harry Lovejoy, Rima Kutner
This melodrama exploits racial tensions with the tale of a light-skinned African-American who impersonates a caucasian and joins the notorious Ku Klux Klan to get revenge on the bigots who bombed a church and killed his daughter. Soon after joining, the vengeful father begins having s*x with the clan leader's daughter.
Available on DVD, but it's out-of-print. You might be able to find it on YouTube.