I had a big long reply to this but lost it by mistake - rats. I take it that you are from a land down under - the other one, based on your username. You won't find facilities here similar to those in NZ and you won't find much in the way of wilderness either. Nice countryside and coastline, but not wilderness. I remember thinking why there was such a difference between the two countries in this regard and I reckon it is because all across Ireland there are townlands which 200 years ago were relatively populous, so there actually isn't a whole lot of the country which hasn't been lived in. 200 years ago in New Zealand there weren't a whole lot of people anywhere and even recent development hasn't made much of an inroad relatively speaking. There are some areas on the West/North/South coasts (of Ireland) but even then they aren't that big. Nice places to visit, but not somewhere big enough to go 'tramping' NZ-style.
You will find that most public places worth camping in will have some sort of bye-law sign up at the entrance telling you that you can't camp there.
If I was to pick one likely place I would suggest Donegal and points East.
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