Why not put lateral delts on push day and rear delts on pull day?
So near or at the end of your push, you could do some lateral raises or some light constant tension elbows no lower than parallel to the ground and out seated db presses. Maybe throw in another side shoulder exercise if it's a priority.
On back day, do some face pulls or rear delt raises.
And band pull aparts most every day in or out of the gym.