"Setposing" them lower will make the light also go lower, so the light still ends up being below the "bulb" of the lamp.
Attached is a streetlamp addon that uses the BIS models, but just reconfigured so that they light by flame with no smoke (use: <this inflame true> to turn on and <this inflame false> to turn them off. The only problem is they do not turn on/off automatically with day/night, but for your application that should not matter. I do not remember where I got the addon, so whoever the author is, sorry for not crediting you. There is a nice assorment of colors, white, yellow, red, blue. I used the red in a mission where I scripted it to blink on and off in unison with the alarm ringing of a trigger (also west detected by east), I put the trigger right near the light. Let me know if you want to use that script and I will dig it up for you. Anyway, the zipped file attached is the streetlamp.pbo. I hope is helps you.