I really think that a scholarly lecture tour of campuses simply explaining Communism has a great effect against these groups. I've actually done it to a small degree; in a university free speech zone holding a sign "Say No To Communism" and handing out copies of
The killing machine that is Marxism.
The students were starved for real information on Communism and I ran out of copies. Almost all far left activism is led by some type of communist. Students just need to know that that means.