I know it's easy to think up game changes and another thing to invent them, but what if....
Basic Concept:
Whenever a battle is initiated, both the attacker and defender would have the option to agree on a new time for the battle. If they don't agree on a new time the battle would just happen the way it would now, 24 hours from the time initiated or later depending on nighttime.
So for example:
The attacker catches up to the defender in middle of the night so the battle is scheduled to take place at 4am. In the battles tab on the strat interface there would be a "Change Battle Time" button. When selected it would bring up a list of all the open battle slots within the next 24 hours. The attacker would then select all the times that would be more convenient for them, so they might choose just one or a range of times like from 5pm-10pm.
After the attacker saves his selections, the defender would get an automated message notifying them that the other player wants to change the battle time. In the defenders "Change Battle Time" menu, they would see the attackers choices highlighted and could either select one and confirm the changed battle time or select their own range of convenient times which the attacker would then see highlighted after also getting an automated message informing them that the defender has picked their battle times.
Once both players confirm the new time, it's locked. Also, the defender would be able to initiate changing the battle time too, I'm just using the attacking side for the example.
Why:
It seems pretty common for battles to take place at times that neither side wants. If something like this was possible it would help cut down on that and the rage/accusations/ill feelings toward other players that go along with it.
