I would agree that you might need to scale down your ambitions a little bit. I think after visiting Dublin, Galway would make a good base for touring the west. Rail travel is reasonably expensive, so personally I would pick up the car when you are finished in Dublin, probably from the airport, before heading west. Local hint...the Dart train service for suburban dublin travels along the coast...head south on it for some spectacular views. It is also worth viisting Wicklow, the county just south of Dublin. Mountainous, with spectacular scenery and easily accessible through organised day trips or public transport.

Feel free to PM if you want any more detail.