Im sure it could have been done at tnight... however at the risk of being spotted ther could be no flash lights or lanterns or not even cigarette lighters to illuminate the activity. The crew's eyes would have to be naturally accustomed to the darkness of night.
this is probably why it took them several hours to do get the fish on board.
im sure it was several hours of frustration and difficult labor. it is very difficult to perform a task in the darkness of night without any visual aides - especially when noise and light are your enemy.
I would say go ahead and load at night in SH3.
BUT
to simulate a more realistic night reloading you should try to load them with the minimum number of sailors in the torpedo room, so that the event takes quite a bit longer than if the torpedo room was operating at max effeciency
