I'm stumped trying to do this.
My eyesight is getting gradually worse and I haven't seen a star since I was 25.
Usually I have all the maps memorized so I don't notice, but with the new Ragnarok and Atlantis, I am bumping into things and getting ambushed as I watch the mini-map for clues to where to go when it is nighttime.
I tried making a potion with a quest directive to set the time of day, but drinking a potion doesn't trigger the "use item" in a quest file.
Any way to do this without using a hex editor?