hey bro, good news. you never have to do a single behind the neck press for the rest of your life, and you can still have cannon ball delts. the majority of my rear delt work is done with bent over DB raises and cables. the only presses i do are with DBs. if you want to focus on bringing your rear delts up, i would prioritize them, hitting them at the begining of your workout. that way, then you do your traditional over head press, you will already have activated the rear delts, and you feel them more in the pressing movement. you can also use a high cable with rope attachment, pulling it with both hands, towards your forehead with both hands, elbows flairing and palms twisted out. i use higher reps for the rear delt movements i do with cables, focusing on the squeeze, holding each rep for 1 second contractions. i feel that small muscles like the rear delts work better with higher volume vs heavy weight. i go heavier on my DB rear raises and go as heavy as i can on my DB presses. i never press with the bar. it limits the natural arch that each arm wants to take and for me, i quickly feel impingement. 

this sport is about finding ways around our limitations. there is almost always another movement you can do to acheive your goals. be creative. think about the way the muscle feels when it contracts and ask yourself, "what else can i do to create a similar contraction?". this is where the ART of bodybuilding comes in.