Well, it might be possible, but it's a complete change of the whole game mechanics. So that is a lot of work.
For me it was always self evident, that "daytime" would only be a short interrupt, not the whole time to wait out. But it would still be an interruption to the action, and require some preparation by the pc. You have to find some shelter to wait out the sunlight.
For the game mechanics it would involve at the very least these changes:
-add some timer to the HUD
-make the timer speed according to the current action and map scale. (I just can't believe that it takes the same amount of time to walk along the museum gallery and look at the exhibits, as it takes to walk from the Last Round to the Empire hotel.)
-calculate the time necessary to travel from hub to hub
-find a way to integrate dialogs into this system
-check if the pc has reached a secure shelter when the time is up
-decide and implement consequences if he has not
... and that probably is only the tip of the iceberg.
And personally I like the game as it is.
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