We lived in Germany for four years... Traveled extensively in our VW camper bus with our two children... Ages 5 and 7 till 9 and 11...
Your itinerary is not one I would recommend... Or one that would have worked for us. It might work sans children on a tour bus staying in hotels on an arranged tour.
Our last trip into Italy we spent 4 weeks enjoying the charms of Italy. We did the same in France, England, Scotland, Ireland, Austria, Switzerland, Spain, Germany, Netherlands.
We lingered in Florence, Pizza, Venice and spent a wonderful week in Rome while camped at Castelfusano. Our kids who are now in their late forties still cherish those memories as Mom and Dad do... As our children and Mom and Dad cherish other countries we spent time in traveling and camping with our VW camper bus.
I really believe you will enjoy and cherish the memories as your children will if you greatly reduce your itinerary...
One of the parameters that governed our plans and travels did not include the notion that this is a one time opportunity...Which I suspect is a factor in the itinerary you have outlined. So we operated on quality over quantity...
JohnnyT