Very intriguing idea! This is how it could work for one person with a car:
Day 1: Holyhead - Dun Laoghaire (2h crossing on hi-speed ferry, €119), arrive at noon, play Portmarnock in the afternoon.
Day 2: Drive up to Newcastle (2h), play Royal County Down, drive up to Portrush (2h).
Day 3: Play Royal Portrush, drive down to Belfast (1.5h), take ferry to Stranraer (€89), arrive 7:30 PM.
Day 4: Drive down to Southerness (2h), play Southerness, drive to Silloth (2h), play BUDA.
Ulrich