I would not advise using a lob value of 99999, it means the ships already visable which can cause lag on low end systems.
Instead replacing the lob entry with this one for fighters and small freighters.
LODranges = 0, 1000
Just increase the 1000 to something higher for larger ships. Start by making a ship 99999 then look to see at what point the engine glow vanishes on larger ships. This means giving the AI the ship and following it with it targeted. If you dont know how to do that, just give larger ships a figure that would appear to be a good distance for them to vanish at.
The only values i use are 1000 and 1300 for bigger ships but i think 2000 might be better for large ships.
Giskard