You are going to have a very hard time doing this for September, which is a heavy travel month, in advance, you are going to have to decide if you are willing to roll the dice, buy the ticket and hope to clear closer to flight time, buy they ticket request nothing and see if you get a decent upgrade offer as you get closer to flight time or try rerouting thru Lhr where there is just a ton more service

ba has a sale on right now so you might even look to see what buying the ticket Bos to Lhr to Naples might cost

the ba sales prices will show up if you book on aa