I wouldn't reinvent the wheel and borrow r/Europe rules as a starting point.
Maybe do a little bit more proactive moderation to that community. r/Europe threads could sometimes go off the rails and had cleanup many hours later - I think it's OK to lock down before that happens (is locking posts a thing on Lemmy?).
Another approach is to keep rules simple and do a complete philosophy and rule walkthrough separately. I penned this monstrosity for polish subreddit back in the day (linking to archived version since I left since then and it got some meh updates in the meantime).
Yet another approach is to have a philosophy page like Tildes does. It's clear enough that you disallow assholery and bigotry but community like this definitely needs submission rules on top anyway.