Oh now someone was posting on POTN.
A search turns up several older threads but not the one I was thinking off. Maybe Paul Iddon or BasAndrews.
There was this thread by Toby
https://photography-on-the.net/forum/showthread.php?p=19556112
Not tried myself, it is on the "try when have time" list.
Thoughts: traditional flash but modern LED touches may be an alternative.
UV flashlight might help spot subjects