I have a rooster that crows randomly at night too-- I live quite a ways out in the country, way out where there's no light for him to be awake to. He just likes to crow at night sometimes! He'd usually start around 3am, even on pitch black moonless mornings...
What I did is I put some sound-absorbing materials in the coop. My parents were throwing away a bunch of acoustic absorbing ceiling tiles and to we lined the inside roof of the coop with them, they are high enough that the chickens can't peck or eat them. They were free, and they helped a lot. My coop has double wall 2x4 construction so the walls are pretty insulated. The vents... well, we need ventilation so there's not much to help that. We also keep him in the coop until a reasonable time of the morning, around 7am, when most folks are up or getting up anyhow (the school bus comes through about 7am so I figured it was a pretty safe time). I can still hear him when he crows in the coop now, but it's much quieter, and you can't hear it up or down the road.
I gave my neighbors some eggs to make peace for the week or two before I fixed the problem!