Yes indeed, the Mormons were very much ahead of the curve. After that 1952 SCOTUS ruling the LDS did jump on it. I grew up in Salt Lake City, and yep, exactly as you describe, directly across the street from the main entrance to my High School ... was where all the "in" kids went. And I was an "out" kid.

I'm not sure if any of the teachers in my school did double duty, but I do remember when the subject of evolution came up in a class, the teacher was very very VERY careful to not push back too hard on all the kids speaking up in class about how ridiculous the very notion of humans descending from primitive forms was. *sigh*