There are a few ways to do this:
Use the stream description to explain what you want for your stream.
Tell the stream mods what you want (and make sure they have good mod history, being on Everyones_A_Mod is good mod history)
I cannot stress this enough: Give owner to people who you trust.

I am sure we can make all the rules we want. They only give limited space for listing these things. The best idea is to avoid auto approve and make sure your stream mods know what you do not want in your stream. But always be as clear as possible when making your stream description.

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I just spotted this in stream settings. Not sure how many rules it allows us to list, but maybe it will get the job done.

i am on a cromebook, actually!