Currently the map and the time of day are lumped together as one vote option.
Making the time of day as a separate vote that appears after map selection will give nights more chances to come into rotation.
In the last 3 weeks, and 60 hours of gameplay, a night map came into my rotation 2 times, this is due mostly to vote diffusion across the map options being so vast to begin with.
Making the time its own vote will remove the disparity from the map votes completely.