The first and only time I ever went fly fishing at night was on the Delaware River, during a FAOL Fish-In!
Ron Kusse, took a large group of FAOL members on this adventure of "Night Fishing", and when we got to the waters edge, the last of day light was rapidly disappearing.
I had a pocket flashlight that had a LCD bulb, and would stay lite for 1000 hours. It also came with a cable attachment (snake) so the light could be setup on a flat surface or wrapped around a tree branch.
I attached this small flashlight to a tree branch, so as the night got darker, that everyone on the river can find where they first went into the water....
Another good method is a "Shake & Break" chemical light tube....
The world looks completely different after the sun goes down, and you lose all you daytime references, for where you are...none of the FAOL members caught anything, but we also did not lose anyone in the darkness!
"Everyone you meet in life, give you happiness! Some by their arrival, others by their departure!" ~Parnelli