This ought to be quite simple to implement, really: when in free camera mode, enable a "flashlight" just like one has in free roam/foot mode (L key on PC). This would make ALL the difference in some nighttime services where one has to shunt or make reversing moves in darkness (especially on Clinchfield!) For those who worry about 'realism,' a) you don't have to use it, and b) I usually envision the free camera in these situations as representing a brakeman/spotter riding the lead car.
