I've done the length of Italy (north-south) in the summertime, and like you, I don't like to plan my night stops ahead of time. I ride along until early afternoon (between 1:00 and 3:00 PM), and then start looking for a place to stay.

You can make that work in August, but not if you look for places to stay in coastal areas or in big cities (which you stated you plan to avoid).

What I do is use phone apps like TripAdvisor and Booking.com to see what is available in the area I want to stay in. This saves phoning around or stopping and inquiring at hotels. "Most of the time" - meaning, about 4 nights out of 5 - I can find an acceptable place to stay within about an hour's ride from where I am when I start looking. About every 5th night, I crap out, which means either paying a lot more than I want to pay for premium accommodation, or paying a lot less than I want to pay for a flophouse, or having to ride for a couple of hours more to get to a location that has accommodation available.

It's hot as Hades in central & southern Italy in August - think 'January in South Australia'. In the north part if Italy (Dolomite mountains) the temperature can be very pleasant. If you want to go to central italy in the summer months, consider staying away from the coasts and riding up in the Apennine Mountains. Much less crowded, far more interesting riding.

So, to sum up, much of what has been said about the perils of riding in Italy in August is true, but it can be done... although August would never be my first choice of month to ride anywhere in Europe, simply because everyone is on vacation in August.

Michael

PS: Get a European SIM card for your phone. I highly recommend the Orange Holiday SIM Card, which is available either as a physical SIM or an eSIM. It works everywhere, and it's fast. Just make sure that your Australian phone is 'unlocked' to enable use of a SIM or eSIM from another provider.