Found this excellent excercise on YouTube done by young star Francisco lindor. It involves a cable machine with a stick at the end that you grip at either end and then you tilt your spine forward and rotate from low to high until the top hand and shoulder is down and shoulders are all the way open.
I did this excercise with a rubber band attached to a fence and the other end to a broomstick. Works just as well if you don’t have a machine.
Excellent excercise for separation, maintaining spine tilt and finishing rotation.