You can put your time into the RTC work but generally face-pulls, serratus push-ups and overhead shrugs will take care of what you need as far as stabilization.
It's pretty likely that you're experiencing some shoulder impingement with overhead because your humerus is beginning to impinge the rotator cuff, most likely secondary to a muscle imbalance betwee your upward scapular rotators and your downward scapular rotators. You likely have strong downward rotators (rhomboids, lats, pec major, pec minor, levator scapulae) with weaker upward rotators (middle and lower traps, serratus anterior) which is limiting normal posterior tilt of the scapula with humeral elevation.
The cool thing is you can go ahead and progress those three lifts just like any other and your shoulder will thank you. Add pec minor stretching in a doorway 2-3x a day as well and you should see some improvements.