That is a tough one. I don't know how weather ready your birds are.
Some people use a ceramic bulb like is used in reptile cages as they don't emit light.
I know my grown birds will avoid any added heat source. My hubs felt bad for a naked hen one year so put a sealed oil space heater in the...
Having a light on will trigger the crowing. Even a neighbors porch light shining into a coop can trigger it. Since yours are in the garage I would say it is the light you have added.
If he is making the females miserable perhaps he needs a country home.
Having just 2 females to the one male is...