I have the water trays in front of the feeding station the hedgehogs use them as a bath / drinking bowl – it has deterred some cats but not all.
The saucers I have tried but unfortunately I have 1 feline visitor with half a brain and knows to knock it off grrr.
We have 3 cats (not mine) coming in our garden and the hogs don’t care. When feeding sometimes a cat will feed from a bowl whilst a hog feeds from another, sometimes they just sit and watch the hogs feeding.
Cats are creatures of habit so need re-educating if possible. They hate water being flicked at them so a child’s water pistol not a super blaster type just a little one. The smallest amount of water lands on a cat and they usually hate it (incl. mine they do like watching running water, drinking it just not it touching them!). If you do it during the daytime it may /may not help.
A lot of us have cats in the garden and it’s a case of trial and error to see what works best.
We had a problem with the cats grabbing the birds of the feeders, we use hanging baskets now which work brilliantly,