If you create such a group, one specific guideline you may find useful, on top of standard stuff like "be civil", is "no labeling another person with any label

If you create such a group, one specific guideline you may find useful, on top of standard stuff like "be civil", is "no labeling another person with any label they would not voluntarily apply to themselves". This helps to weed out subtle incivilities, like calling people anti-whatever, that people might otherwise feel like they can get away with.