Sounds like a good trip, in my experience, going from the Ring to say, round about the Lake Como area is a 400-500 mile drive, now if you're planning to take a partner/wife/girlfriend/blow up doll, I would take at least an overnight or 2 night break on the way down. Reason behind this is even on an early start, you'll get into the Alps, late afternoon, by that time you'll be pretty kanackered and the ladies will not enjoy it and neither will you.
These are great trips to do, but I would stick to 250 max on driving days, take 2/3 night breaks between driving/exploring the passes, I've spent a few 12 hr Alpine drives, wishing I had stopped earlier, like 8 hrs earlier.
Just a thought, if you're a driving monster then go for it in a one'r, but after a track day as well....
Any of the Lakes are a great base, but Italy is HUGE, even from the Lakes to Bolognia or Modena is a fair old treck. Also, plan the return trip as detailed as the outward one, been there on an evening on an Autobahn, with heavy German traffic, can be very congested, I would come back up through France.
Just pointers for you to take regard of if anyone wants to take you up on the trip and takes along partners