I don't even know where start with this. Clearly you have never been raped. I am a 5'7" extremely athletic, strong individual, but I could not fight off a 5'10" man of average build who tried to rape me. Bully fir you that telling a man to back off magically protects you, but it's absurd to think this would deter a sex offender such as Ian Huntley (who now identifies as a woman). Do you not think that Hollie Wells and Jessica Chapman begged him to 'back off'?
Thanks for the assumption, but in fact I have been raped. Systematically for 4 years in an abusive relationship, and once more violently by a ONS last September. Do I qualify to have an opinion now? 
Of course I'm not saying that 'back off' magically solves the problem. I was making the point that I am frequently in spaces where people are freely wandering around nude, getting changed, showered, and dressed communally. I.e. the nydist/swinger/fetish scenes.
What I'm seeing is that in that in those situations, there is actually a huge amount of respect and a very good culture. As in, if a bloke asks something inappropriate I say back off. I've been taught in these communities to act with confidence and always be polite and kind. As the men are taught. If they don't back off they are told off/removed/shunned.
Basically, I have observed that when the taboo and the mystery around bodies is lifted, people act with a lot of respect. That men perhaps aren't the bogeyman people view them as.
I feel much safer in a swingers or fetish club than I do in a normal nightclub, for example.
I don't really see what Jessica and Holly have to do with gendered spaces, at all.