If you don't have an electronic logbook do it the old fashioned way, do you need the instruments lights to see them? That's night time. It can be a long time after sunset at altitude. Not does the lights make it easier but is it impossible to fly without the instrument lights.
U.S. to Europe is all night time in the winter and less than 4 hrs in the summer time.
Where's the regulation stating that 51% night time allows you to log 100% night time? I love to interview guys with fake time in their logbooks.
It's like IMC logging. You can't see a cloud and log instrument time. Flying above an overcast isn't IMC. Flying between layers isn't IMC. Guy said 30% of his jet flying was instrument. With leg/sector sharing that meant 60% of his jet time was IMC. He'll never get hired.