When we crossed over from France into Italy, we headed along towards Venice, stopping the first night just South of Arona on the bank of Lake Maggiore.
Campeggio la Quercia di Bucelloni
Via del Lago, 42
28053 Castelletto Sopra Ticino Province of Novara, Italy
0331 923085
campinglaquercia.com
We found it late at night, after a very frustrating hunt for a 'Aire' which was in the ACSII book - which turned out to be the entrance queue area to a Safari Park, with no facilities at all. We finally found a strip of 'civilisation' which included a "Golden Arches" - so we dived inthere for a coffee and some free wi-fi, and found that the nearest campsite was just a few hundred yards away. We arrived as it was closing up for the night, and they couldn't have been more helpful. Nice clean site, usual ropey Italian electrics!
Are you going over the Col d'Iseran once you are in France? Highest pass in the Alps.
Edit : I was advised (correctly) by Alan (Dandwarhol) on here that Garda and Como are best avoided in August, as they are incredibly busy, and are turned into one-way systems, which is very tedious. He advised skipping past them to Slovenia, and going to Bled instead. Sounds like you will be doing the same trip in reverse.