I think the problem of cats on balcony's/veranda's is due to some guests feeling the need to feed the cats. Cats being cats will go where the food is or where is was the last time. If guests did not put food out for the cats and left them their own devices to find food naturally or if CSA had designated feeding stations for them then they would stay away from the balcony's. We had two cats sniffing around for food at our balcony one day, we shooed them away and they never came back because we did not put food out for them, obviously the previous guest must have. So don't feed the cats.