After reading this thread for the last several days, I've seen a constant referal to the stern being a "designated smoking section".
I've been diving for a little while, and I haven't heard this once during a boat briefing.
This is not a slam on either side, just an observation that I obviously haven't been on the same boats as you.
Also, I know there are good folks out there; the considerate smokers try their best to smoke where it won't be a problem, and the considerate non-smokers do their best to move away from it and not be pushy. It seems the inconsiderate folks, of both sides, are the ones we remember and paints the stereotype for us.
It also appears the smokers are in disbelief that the small amount of smoke they produce can be a problem. Obviously it is. Also, it's obvious that the non-smokers can't understand that it is difficult for smokers to go without for 4 hours. Just as obviously, they can't. Being considerate means understanding the other person's needs, too.
Not taking any "sides" here, just observing.
All the best, James