Weatherproof stucco will not withstand the heat of a true Neapolitan oven. You could tile it to put it in the rain, I guess, but they are better used with a roof over their head. The more pictures you post of the Italian builder's in process pictures, the less respect I have for their skills. Any of the DIY builders on the Forno Bravo site are building works of art compared to those Italian "masterpieces", and they are doing it with much higher performing ovens, i.e. they insulate.
The best of both worlds is achievable, but so long as they stick to so much tradition it will not happen. This is not to say that the traditional oven does not perform, it does, but it could perform by a couple of degrees of magnitude better if built with modern conceptions of oven building and insulation.