I understand your concerns, but I think they are addressable.
> some people’s skin is far too thin
This is a valid point, trying to make everyone conform to most sensitive person in the room is impossible (imagine someone being offended by low-cut neckline in woman’s clothes). However there is no need to do that. Agreeing on some reasonable standards and being eager to say sorry if you hurt someone unintentionally is enough. Just make sure that people with all kinds of experience are included in the decision what “reasonable standards” are — I doubt you (or me) alone can make this decision.
I think that explicit policy is benefiting all the sides. It lowers the chance of unintentionally harmful actions — less people hurt, less people punished for something they did accidentally. It also puts the norms up for public discussion. It’s way better to discuss well-defined rules instead of assuming what “feminists” demand and discuss the a man.
Other thing that would benefit everyone would be giving each other benefit of the doubt. If you don’t assume that every penis joke was done to harm you, and just ask not to do it, life becomes easier for everyone. If you don’t assume that a person asking you to change the topic of your jokes is “actively seeking offence”, but believe they are genuinely uncomfortable, again, both your and their life becomes easier. Unfortunately, in current reality of constant mutual escalation and blatant generalizations this sounds like an utopia.
[Upd.] As for “open discussion” (as opposed to one limited by code of conduct): conferences have a topic, I doubt any code of conduct would limit discussions within this topic (especially for technical conferences). If you need a space to discuss a controversial topic, create one and put a code of conduct in place there that would allow all opinions on that topic.