Better rehome them or try a no crow collar... My boys start at 3:30 EVERY morning for the past... since they started crowing.

Not an issue for me or my neighbors... fortunately! If my neighbors have issue, so do I and I work very hard to be a good neighbor. Which I can tell you want to be also. Maybe let them know that you ARE working on a solution. Maybe they will be able to be extra understanding if they do know that you ARE going to remedy it one way or the other and just need a little time to figure it out.
Dark has nothing to do with it. They crow at sound, and for all kinds of reasons including letting predator know they are protecting their flock.
Careful with the crow collar if you go that route, I've seen mixed good and bad experiences.
Good luck!