Lievito Madre and Panettone question

Getting ready to make Panettone, haven't done this in a few years. I've been building my Lievito and it is now at the point of tripling within 4 hours, but after a few more hours it peaks and starts to collapse.

The Massari recipe has a first dough with a 12 hour rise, followed by a second dough with 4 to 6 (IIRC) hr rise. The first time I tried this, it didn't work, the first dough rose well but seemed overfermented, sticky. The second dough lacked structure and the end result was under-risen and dry. I am wondering how the starter can work on the dough over such a long period without overfermenting.

I am now working harder to build a very active firm (45% hydration) Lievito Madre, in the hope that it will help. Also, I was using Galahad flour, which I think doesn't have enough protein. I've bought a couple of types of 00 flour, but they are only 12%. Thinking of mixing with All Trumps, which is 14.2%. 

Any advice would be much appreciated!