dear Tod,
now I better understand the "dilemma".
Following also Ferdinando's advice I've had a look into my books finding a lot of photos of officers and NCOs of Regia Aeronautica in the early thirties and in the war period wearing the estiva uniform but every time I've had the same sensation of a wrong "look" that you have. In particular I wasn't able to find an example of a three buttons tunic (that however doesn't mean that such a tunic doesn't exist).
If you want to have a look to some photos of Italian "estive" of the thirties you can go to the site of the "associazione culturale quarto stormo"
www.asso4stormo.it than go into the "Quarto stormo caccia section"
www.asso4stormo.it/arc2/link021.htm and have a look into the photographic collections of -at least-: Mario Bandini, Albino Cagliari, Raffaele Chianese (first and third part), Franco Comelli... The site has really many interesting photos and not only for the uniforms.
Kind regards,
Ludovico