The lighting settings of the lightposts are controlled by .ini coding.
The game's internal name for the invisible green lamppost used in so many maps is [INGRNLMP].
You could paste the following coding directly into your map (after opening it with Notepad or Wordpad)
CODE
[INGRNLMP]
Name=Invisible Green Light Post
Image=GALITE
Selectable=no
InvisibleInGame=yes
Insignificant=yes
Strength=6000
Armor=wood
TechLevel=-1
Nominal=yes
Sight=0
Points=30
Power=0
Crewed=no
Explosion=TWLT070,S_BANG48,S_BRNL58,S_CLSN58,S_TUMU60
LightVisibility=4000
LightIntensity=0.01
LightRedTint=0.01
LightGreenTint=1.5
LightBlueTint=0.01
DamageParticleSystems=SparkSys,LGSparkSys
Powered=true
And then change the settings to you liking. I'd suggest decreasing LightVisibility (radius of the light) to 3000 and the LightGreenTint to about half the current value, see what that does for you.
Please contact me on msn if you need me for anything, thanks.