Days 3 & 4 - Saturday / Sunday (360 miles / 9 hours driving time)
Day 5 - Monday (130 miles / 3 hours driving time) would see us head over to the Grossglockner. The hotel is at the peak, so you can drive the Grossglockner at night time, numerous times, if you wish
There is quite a lot to explore on the Grossglockner and it can get quite busy, so can easily spend half a day there.