No amount of prep was going to help that train wreck -- Johnson never had a reputation as a particularly smart politician (he was rather proud of his ignorance, actually), but he showed less knowledge of world affairs than the average evening news viewer. And he's still the most credible candidate the Libertarian party has posted!

If you want libertarian views to gain political credibility, you'd probably be better advised to try to start within the GOP, especially given the state of factional conflict likely to follow Election Day. Libertarian, moderate and the few remaining Rockefeller-style Republicans are the only ones who have kept their hands clean when it comes to Trump, and who have an arguable basis for reconstructing the party -- though it would be a long slog to do so.