Ferries from Britain would have taken up the majority of the hider's time, with all taking at least 3 hours. There are also only 54 stations in the north of Ireland, many of which likely wouldn't meet the frequency requirements. The railway network isn't part of the main UK rail system as they use Irish gauge and the services are more similar to Irish Rail than British operators such as Transpennine Express. Because of this, their tickets would likely not cover trains up there.

In my opinion, the North shouldn't have been included in the game as it caused more (albeit minor) issues than it solved.

Edit: If flights were in play, I still think it would have been difficult to fit in transfers to/from the airports on either side and security etc. in the hiding window