By showing the jets, you'd be giving away the player's position, so I assume you are wanting to make the players less visible when in the dark and easily seen when in the various lights in the map.
You could acheive this in a different way by, as many others in this thread have said, make the polygons back and the background black but also adding a stretched black "blank" scenery at a opacity of around 70% over the front of the dark areas of the map.
To have lights, you would need to leave gaps without the black scenery, making a soft edge around the gap like a frame using black "fx_li_beams" set to the position "back". Then you'd add in your light in this frame, set to back but also behind the beams. Lastly, you'd add in a second light over the top of everything (at "front") with an opacity of 30%.
To have the scenery showing at whatever visibility you want, you'd need them to all be set to "front" otherwise they would be showing at 30% opacity due to the "blank" scenery.
This is just an alternative way of doing something similar to what you wanted to do. I hope it helps!
