Scrider, it' s about discipline. You' ve done your practice. You' ve hunted so you know the adrenaline rush and the heart beats sometimes makes some people take shots they shouldn' t take. Make yourself have a mind set where your not going to take that first shot unless the deer is broadside and in easy range. When you make that double lung shot, the deer will be dead in just a few seconds. He may cover 30 yards but it' s over quick. I' ve gutshot one deer that took me two days to fine. It was my fault and now I' m a much more disciplined hunter. If I can' t double lung it, I ain' t shooting, obviously alot of deer get by me but like you, I' m not into animals suffering.
To gain confidence in your ability, try taking your target in the woods, climb a tree with your bow and practice in the woods. Have your son move the target around so you see the different perspectives of range through the trees. Another thing, get you a range finder and eliminate that part of the equation. I admire your ethics and like Taz said, you' ll make a good bowhunter that all of us would be proud to hunt with.