I think I have a useful variation of BB's idea for night shots, at least for P8+, since it exploits IDL.  My Lothlorien-esque stairway models have a lot of lamps, and dealing with eighty point lights is a chore (and a render burden).  :(   I recalled the thread here regarding ambient-textured geometry used to light a scene, but the panels had to be searing blown-out white, even though the light they cast was modest.
     After several trial experiments, I finally managed to get an idea to work:  an intense IDL emitter hidden inside a gently-glowing lamp.  Using this method, you only dial the default scene lights down;  no other lights are needed - the emitter geometry does the work in IDL.  For day shots, you need only uncheck the visibility box for one item - the emitter array is a single prop. :)
     Here is a test render of the top flet on the gnarly mulberry;  default Poser scene lights are dialed down to 8%, rendered in P8 with 4 raytrace bounces at 90% irradiance cache:

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5