For the longest time I've had issues with the Corona's, they'd show through my lightbar mesh, and just not look nice.
See image for example:
In the carcols.meta there is a variable called "pull", you can find it under the corona category. If you put this value to 0.0, it won't allow the corona to pass through a mesh. I tried this, to see if it'd still kick in after looking at a vehicle from a certain distance.
Check this video!
As you can see the corona shows only at a distance and not up close.
For the best effect you'll have to have the axis for Non-ELS quite close to the mesh, but still behind it, if that makes sense. Now you'll have the corona's at a distance, that way you're emergency lighting is still visible and you'll have proper lighting up close.
Unsure if this is the right category for this, if not please let me know. 