No you cannot hike on Camelback Mountain at night as it's strictly prohibited and if caught hiking the Camelback Mountain at night you'll get into trouble.
That's because it's very unsafe to hike the Camelback Mountain during the night as severe people who have hiked the Camelback Mountain have been rescued off the Echo Canyon of Camelback Mountain during the night.
So you really should not hike the Camelback Mountain at night even if it were not prohibited which it is because you risk getting hurt, lost or even killed.
Only go hiking on the Camelback Mountain or any other hike during the day whether it's prohibited or not because it's much safer to only hike during the daylight hours.