Hey Tindahbawx,
It shouldn't be impossible. Uboats preferred to sink targets under the cover of night. Daylight, especially with the new mod updates, is dangerous.
I've seen some nights myself where it was difficult to see the targets, but that's not the norm. I don't play hardcore like the others, and have often wondered how they manage to even identify a ship's flag in such darkness. Masters of the deep, they are, says Yoda!
With a full moon and stars, it's beyond me as well why you can't see anything. Those conditions, with your target between you and the moon, would normally be optimal.
How about your monitor? Do you have your gamma and brightness set properly? Are they set too low maybe?
Other than that, I'm not sure what to tell ya.