I trust in our ability to think up ways of avoiding this. The same way Jiu Jitsu, a lethal, murderous martial art, was redeveloped into Judo, a far less lethal version, I think we can use our sense of rationality in such a way as to develop an art of debate that doesn't need to rely on the Dark Arts to persuade the audience

I don't trust anyone's ability to avoid this pitfall. Rationality skills are often learned on the 5-second level, so it's paramount that we train ourselves to not instinctively rationalize things. In general, when persuation takes precedence over truth-seeking, then you're no longer talking about rationality, you're just talking about how to win debates. I agree that there are white-hat ways to debate and black-hat ways to debate and that public speaking is a valuable skill, but rationality is never about arguing for a particular conclusion. As a result, I think it's best to keep the two concepts separate and be very mindful of which thinking skills you are using for each activity.