I use Dr. Cook's Bitless Bridle. Mechanical hackamores work great as do bosals. As with a bitted, you need to be aware of your hands. Any bit/bitless can be dangerous in the wrong hands.
What is your horse doing that leads you to believe he might do better bitless?
I know with my draft he was real fussy in just about ever bit I tried with him. I finally gave up and went back to riding him in his halter (I broke him using his halter because I couldn't find a 6" bit). I found Dr. Cook's bridle and he's just done exceellent with it.
Much more relaxed.