In the event that I meet a member of the carabinieri or policeman in other than a social setting, what would the proper greeting be? Signore? Or should I offer an on-the-spot promotion and address him as Capitano?

I wouldn't give them any more delusions of granduer than they already have Steve. Try "Oi, scemo.. vieni qua".

Well I would probably avoid using Aliena expression unless you are looking for some trouble.
I would avoid Capitain since it is a rank - Unless you know rank in Italian uniforms, just use the 'lei' - the formal Italian - Or English -
PS I was a Carabiniere once upon a time

Paolo!! You have a hidden past life! How mysterious! LOL

Aliena! You were so helpful when I was looking for Sagre e Festa informazione and now you try to help me into jail!! Scemo! - that would be me!! ;-)

Paolo - grazie. We once stayed in an appartamento owned by a retired Capitano Carabinieri in Corciano, just outside Perugia, for a week. He was very helpful and proud of his service. Not only that but there didn't seem to be any crime in the area around his house... ;-)

Haha Steve.. it's just my warped sense of humour. I'm sure you knew that it wouldn't be wise to address anyone by using "scemo"

I just think of your comment as a contribution to my understanding of l'italiano - another word in my quiver. E, force, I might actually run into un scemo and will now know what to call him..from a distance...or from a fast car!

Use to work with Carabiniere in Vicenza years ago.
They told me they made very little money back then.

This past summer got pictures with some Carabiniere.
They were polite about it.

Paolo, How much money do Carabiniere make?