You could do this, if everything sticks to plan, via public transport - the new metro to Forlanini, the Passante to Cadorna, Centrale or Bovisa. It can be done in 90 minutes. Use Google Maps at the time you are there to get the best of the multiple options. If you don't know Milan then a taxi should take about an hour, but if you wear spectacles you should take them off, or tell the driver your flight is the next day.

I don't know if you have an option to move the flight to MXP by doing a fare difference?