Oh duh. All I had to do was change my location.
Sigh. Facepalm. lol
So, I was sitting here wondering what solutions I have available to me to get 1200K for those times when I got to bed during the day (so, before sunset). I started thinking that I could just change my computer's clock, but that would be extremely inconvenient because I rely on it very heavily. So, I kept thinking and thinking and thinking, but nothing was coming to me.
So, I have been trying to figure this out for several days now because I knew there had to be a solution. Well, it suddenly hit me and then I facepalmed: all I have to do is change my location in f.lux to make it think that I live in a place where the sun has already set! Duh! lol
This works perfectly for me because I already exclusively use f.lux manually, meaning that I never allow it to transition automatically. Instead, I wait until I know I will be going to bed in a couple of hours before I change it to a warmer color temperature. For the longest time, I was frustrated because whenever my bedtime ended up before sunset, I could only go as low as 2700K (or 2457K or 2513K if I use Alt+Page Down as far as I can tolerate with this monitor). So, my favorite happenstance bedtimes were after sunset because then I could use the "Lighting at night" which would give me the freedom to choose 2300K, 1900K or 1200K. I've been preferring 1200K lately, so it has been extra frustrating, hence the extra effort that I put into figuring this out.
So, now my palm is attached to my face in a long facepalm just saying, "Wow. All this time and all I had to do was change my location in order to get f.lux to think that it's after sunset so that I could use the Lighting at night option. Geez."
So there you go. If you are in the same boat (or at least a similar one), then just change your location in f.lux. All it might take is a simple change of the secondary coordinates (the one that says either "W" or "E" after it. Try different numbers and after doing this a few times, you'll begin memorizing certain locations that always work during the day! You will never need to do this at night in order to simulate daytime because you can ALWAYS choose 6500K any time you want. See?
Of course, you can also use Google to help you figure out where nighttime is any time you want.
Edit: I'm currently telling f.lux that I live in Ghana, Africa (lol I didn't try to select that). Specifically, I randomly chose 7.13N, 0.36E. So now instead of f.lux thinking that sunset is in 5 hours, it says that it was 3 hours ago! It feels good because now I can get ready for bed with my preferred 1200K setting!
I simply used Google Earth to show me where the darkest part of the planet is right now, and I went with some random spot in the middle. lol Well, that would be Madagascar, but then I ended up messing with the numbers for fun and I ended up with this. lol As long as I can use 1200K for the remaining 2-3 hours before bed, that's all that matters to me, each and every single day.