Don't do it! The shoulder on a bear is lots thicker than a deer. It won't work well.
Your set up is adequate. Hunting over bait your shots will be close. Don't rush the shot. Wait for a quartering away so you can get both lungs.
I've killed bear with a bow and they don't seem to be too hard to kill. But, there's nothing like trailing a wounded one that wasn't hit well. Pucker factor galore!
Another thing you might want to try is a string tracker. Bears don't bleed very well with their long fur and all that fat. Makes tracking very difficult.
