Thanks so much!
There's two things that I will be implementing soon to help with the issue you're having:
1. When you hover over a segment of a traffic wheel all the traffic lights on the map will change colour to the highlights phase. (This was suggested by someone in the discord)
2. Something similar to what you're suggesting. Either exactly as you describe it or a button that overlays a smaller version of the traffic wheel over each tile with a traffic light.