If you have the backside of your figure illuminated, then the problem must be with your reflection setup. Be sure that the reflect node is plugged into the reflect channed of the Poser Surface. Make sure that the diffuse color is BLACK. Make sure that reflection value is 1.00 and that reflect color is white, and UNCHECK Reflect_Lite_Mult AND Reflect_Kd_Mult. That should give you a mirror with full reflections which is unaffected by the lighting. I have done extensive work with reflections is P5 and I can assure you that they work fine. Of course, in render options you must have raytracing on.