You are a nice guy, and nice guys want to "fight nice." I am an old school anti-war democrap who has become rather grumpy in my old age. "Fight Nice" didn't work in any recent war. But the balkanization of Yugoslavia sure did. So, if we are forced to enter a war that everyone wants but is too afraid to act, well let's do it and let's not prolong the war like Afghanistan. My most humanitarian solution for Iran is just to bomb the hell out of them until they emphatically want to unconditionally surrender and accept balkanization. My second best solution is to allow Israel to nuke the entire country, problem solved forever, and America doesn't get blamed for using nukes. Solution 3 is so horrific that I think Iran would easily prefer option 2.
Understand I appreciate your post, but disagree with most of it's content.
Allow to explain ....
I may be a "nice guy", but I prefer to fight smart and fight efficiently (not "fight nice").
Along with being a historian in general, I consider myself a military historian in specific. I also try to be an ardent student of Sun Tzu, and other strategic thinkers. When it comes to tabletop 'wargaming'/'conflict simulations' I've been know as a rather unorthodox tactician and strategists.
My approach to a situation like Iran (and the world and history are filled with many similar) is to realize it is not the whole nation nor the whole population we are at difference with, are at war with. Our enemy in Iran is a minority of the population, one which is a fundamental religious extremism and which is in control of the government, and military, which is trying to balance control and domination of the nation's population while directing the nation's resources towards and outward, global agenda of fulfilling the religious mandate of the dogma it lives by.
Our (USA) objective and goal in dealing with Iran is to remove significant and most dangerous amounts of it's military might, thereby reduce it's threat capacity towards it's neighbors and the world. We also should wish to see major regime change in both actual leadership(ayatollahs and mullahs) and also government system/method - Islamic theocracy dictatorship.
Best methods to achieve those objectives is to reduce/destroy it's military weapons capability, military leadership and organization (including C3, support, supply, and resources), and eliminate the political structure of the theocratic government. Then encourage, arm, train, and advise the populace in insurrection towards the current regime and assist in it's replacement with a more civil, democratic, and secular form of government and leadership.
These are the tactical, operation, and strategic processes for Iran. In a broader and Grand Strategic style we would consider how to invalidate the ideological and dogma foundations of Islam to render it an impotent, insane, and useless theology/religion.
Once the above have been done and/or set in motion, then a regime change and governmental restructure can begin within Iran.
It's way past my bedtime so I'll have to cover the more specific details of how to at a later time