What an incredible vehicle to explore the Emerald Isle off the beaten track! I'll see what I can do to point you in the right direction. 😊 Do you already know where in Ireland you'd like to explore with your rental Defender?
The Camping Ireland website
lists campervan rental agencies that might offer 4x4 vehicles with roof tents. Even though they usually have motorhomes and regular campervans, it doesn't hurt to ask if they have what you are looking for.
Another option would be to rent a 4x4 vehicle
and a roof tent separately. The agency Overlanding Ireland
(in Co. Tipperary) offers this type of tent.
We also have tips on camping in Ireland, driving
and campervan travel
that might be of interest.
Let us know how it goes :)