Personally, I think the villan theme would have seemed very cheap. To keep with the time period, they would have had to use cutouts along the track which seem cheap, and if they decided to do AA's it would be too high tech and take away from the elegant simplicity.
What I would do is install trellis along the hills like this and then have clear plexiglass run along the side closest to the outside world. I am beginning to wonder though if the scream tubes are more to block views of outside the park than to stop sound. The point about Knotts not having anything like this is a good point.
Anyway, my quick sketch: (brutalized by the file compression)