I don't believe that place exists on the Internet. There are lots of books/papers/talks on why that is but they boil down to 'problem' people spend more time creating problems on the Internet because it makes them feel better about themselves. 'helpful and polite' people spend more time actually getting things done because that makes them feel better about themselves. So combination creates a disproportionate share of 'problem' people in forums and other online communities.
Create an invitation only version of Stack Overflow perhaps and require 100% full transparency on participants (real names, job, and affiliations). Experience with those sorts of communities show that folks will be helpful and polite (generally) but the community will not be vibrant or large.