Just to let you know - Principal LED makes a 3 channel dimmer for their leds - Not sure if it dims all the way to zero but you would be able to dial in a much lower intensity - have the building dept. come out with their light meter to prove you wrong (or make adjustments).
I've had 2 similar situations - on the first one - replacing a face from an existing cabinet running T-12's - They required a lighting spec on the application - I just made guess to fulfil the permit app requirements, they never checked. Total waste of time trying to figure out the fc's. On another job that used all white faces on a channel letter sign, it was also brought up, so I told them that a dimmer would be installed and that they could be there when i adjusted the intensity to their liking. I never heard any more about it and the LEDS were left at full brightness. I should go back and pull the dimmer for future use on another job.
all in all I understand the need, but until the industry and the building departments tighten up their game with some standards that are understandable, I'll continue to play my game.
Good luck - hope that helped.