It looks like you need it to be more opaque on the ‘axis’ of the actor?
Maybe you could measure the distance from that vector somehow, or, I recall BC talking about ‘wetness decals’ and a lot of masking going on there, could it have been that?
Be aware, that the player can’t walk into the god rays, as the illusion totally breaks down then. If you want that, you have to use a real volume.