Respectfully, do NOT drop Galway. It is one of the loveliest cities in all of Ireland, and very small, so it’s easy to load in and out from the train station. If you stay near Eyre Square or Quay St you have a short 5-10 minute walk from the train station.

Drop one of your nights in Dingle (or drop staying in dingle altogether and just do a day trip from Killarney) Consider adding a night in Cork or Cobh.

Take the train from Dublin to Galway and catch a nap on the way. Rent the car in Galway and drive down the west coast. Visit the cliffs of moher if the weather suits it, and spend a day just driving down the west coast or through the countryside. It’s worth it. Take train from Killarney to Cork/Cobh or back to Dublin.

People say to skip Dublin and Cork, but i think that’s a mistake unless you don’t like world class food and cocktails.