I've been lucky in the past, when hiring a car from Zurich and dropping off in Marseille with Hertz, they offered me a French registered car which had to be returned anyway, so they waived the one way fee, and I got a better car as well.
So if your hiring from a major centre in Italy, use one of the big companies and you may be lucky.
Similarly, this year I need a car from Geneva to Nice. By hiring the car from the French side of Geneva airport, I can avoid the one way fee as it doesn't apply within the same country.