A bit offtopic, just interesting, I though a bit, devs said it's out of engine to make day/night affect to hit%, but isn't it a problem to make "Night Person"-like trait automatically added to every character from begining (of couse make it invisible in character sheet if possible) and simply make it work like Sharpshooter perk, which will modify your FoV and bonus to hit during night and day? Like +0 PE to hit and +0 PE for FoV during day and -X PE to hit and -Y PE for FoV during night.
Also if it's possible to make it work in some locations like caves, just add some variable in perk(or trait, whatever) conditions. This way all characters will have reduced FoV and %to hit during 18:00-6:00. Night person trait can be reworked that you partly ignore it, but have some other penalties during day, this way, if TC (or other popular player interaction stuff) going during game night, it'll have different playstyles. Night vision stuff can remove that perk from character or add anti-perk that will work the same way, but +X and +Y to PE during night to compensate it, so, for example holding FN FAL NV in main slot will give you night vision perk, so you can snipe people at night and kill them from where they don't see you!