Personally in the time you have I would give the Romantic road a swerve. The only bit of it that I found worth seeing was the last bit in Bavaria around Fussen and the lake there. I have done the Italian Lakes in August and it will be extremely busy and sites will be at a premium. Aires are cramped and expensive. You may need to book ahead for some of the hot spots and be prepared to pay top prices. We have a scooter so I found aires and places within ten miles of places like Lake Garda. Iseo we couldnt even find space on any of the Aires / Sostas (There are not many). There is a good Sosta at Cannobio on Maggiore and one to consider not far from there is Lake Orta which is a bit of a hidden gem and a bit more low key than the likes of Garda. If it gets too much the Italian Dolomite's are worth exploring.
I wrote this blog in 2012 which is mainly the Dolomites but also some of the lakes around August time. Its a fantastic place.
Italy
sites.google.com