AFAIK, one is enough.

Have been knocking into farmers local to me but no luck as of yet, hopefully soon

Are there no farmers you know personally? I can understand why asking a farmer you don't know would be reluctant. If not, is there a gun club relatively near you? Joining that will do if you don't find a willing farmer.

You might find this of some help:

https://www.nargc.ie/cpages/how-to-join-a-club

As they say, with 950+ clubs nationwide, there is one in almost every parish. There could well be more than one near you, but they generally don't have an online presence so you can only find them by knowing someone. I was lucky, my dad was the secretary of our local one :)

Get cards with your name and number on them and go knocking on doors. Has got me half a dozen separate permissions