Just wear non-skimpy clothing (e.g. business clothing or jeans+sweater), and if someone really sexually assaults call the police, while otherwise tell them to fuck off.
Surely there's more "sexual assault" at an average dance club than at an hacker conference.
Now perhaps nerds are worse at reading cues of unwillingness by women than the general population, but that's kind of fixable by bluntly saying "I don't like you" or the like, and then nerds are probably much more likely to take that at face value and desist rather than as a test of whether the man is insecure and gives up easily.
Although maybe conferences could hire more security people from reputable companies if there's indeed such a problem.