It is NOT hard to find off the path destinations in Italy without a car. You just have to go to places where the train stops that are not overrun with tourists. Ferrara is not overrun with tourists. Treviso is not overrun with tourists. Almost any town on the coastal train line other than the five Cinque Terre towns and Levanto gets no English-speaking tourists and they are lovely (Moneglia, Sestri Levante, Chiavari). There are even stops along the train line (or a combination of train plus bus or taxi) on Lago Maggiore that are not overrun with buses full of foreign (Baveno) but are still convenient to all the sights.

If you don't want to go where other people go, don't plan your trip around an international guidebook. Dig around the internet.