You may very well make yourself very unpopular with your neighbours re cat poo in other peoples gardens!
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That is a suburban problem, not a rural one.
You may find that if you 'build it, they will come'. In most rural areas, there are cats about, and if you provide a warm safe spot to sleep, one will quite possibly turn up, at which point you can start to feed it to keep it around. But you may find you get a stray cat rather than a feral one.
There's a vast difference between stray cats and feral ones. Ferals are rarely seen, charleyfarley's cats were very likely feral. We had a stray cat this time last year that we managed to catch with her kittens. We'd been told she was feral but when we actually got to handle her, she was just a very timid cat, not at all wild. Ferals don't generally want to be pets, strays do and will move in to your house if you let them.
To rehome a feral and care for it properly would be a great thing to do - I wish I could offer to here, but with 3 lurchers, I doubt the cats would stay around very long.