Shooting at night sounds like trouble waiting to happen, to me. I think most any organized range would frown on it.
Tracers are very visible at late dusk. This is when I have always shot them.
Keep in mind that most tracers don't light up until almost the 100m mark. To shoot them at any less than 300m is a complete waste (unless you have .22 LR tracers), and 600 or 800m is best.