I have won a few national and one world title in bench press and have trained several atheletes. One excercise that works all parts for archery is front pulls with straight bar. Use straight bar with close grip in front. Pull the bar all the way up under the chin with elbows up high past ears and return down slowly. This excercise works back, traps, shoulders, forearms. I do agree that pulling bow while shooting will gain strength eventually also.

If you have access to lat machine it will work the back, use wide grip when working back.