I originally had blue phantom lights, but those were too dark. I might try to mix some orange and blue ones and see if that helps.
I would suggest looking at the phantom lights of pipeline. For open areas they are very good and give a good natural light effect.
Note that you dont have to adjust all lights to be halloween colored. In skullcove i mainly used normal lights and the only phantom lights youll find exist in the spawn (the red glow at the upgrade station and the blue cave effect under the spawn)
Also, at the final pit i would actualy make the deathpit in such a way that it more often would help the blue team rather than anoy them. So what harribo said is actualy a good thing to anoy engies but then again, if its too large a red pyro can easily airblast them off the point and into the pit. So i think it would be unrecommended to make it go all the way around.
I would place the deathpit where the stove is now and another deathpit under the wood at a same size. This would allow both teams to have some effect of airblasting and at the same time not totaly destroying the red defense options (and if that was your idea, just have some random ghost spawn to at least give the blue team the chance to wait for the ghost and then attack in while the defenses are weakened)
And at B i actualy would have a pit under the table. One which you cannot fall in though. But it could be a nice source of light to highlight the control point a little (by for example having some red glow coming under the table).