I'm surprised how mixed these responses are. A runway condition check after dark/before sunrise is completely reasonable, especially at rural, low-traffic airports known for wildlife. Most of the time, an Ops or ARFF vehicle will be up on freq and roaming around anyway, so it's no trouble for them to accommodate. I used to do this at State College, PA for those 5am pre-dawn departures. Even if there weren't ground vehicles willing, I would still back-taxi at least to from the rotation point for the peace of mind. Plenty of busy, towered airports do frequent runway inspections in way more favorable conditions, so it's really not an unreasonable practice.