I recently replied to someone else with a rat problem which you might like to read.
Other than making life difficult for the rat, there isn’t really any way of getting rid of it without putting the hog at risk.
I have a similar problem here at the moment. The hog usually visits about 4 in the morning.
I have been reliably informed (by someone who actually sold that sort of thing) that those rat scarers don’t work on rats outside, in anything but the very short term (too many other distractions). As you have discovered they soon get used to them and ignore them. I, also, am not totally convinced that they don’t affect hogs at all. I left one on by mistake one night and saw a hog visibly flinch when it went past the rat scarer. The makers cannot definitively say they don’t affect hogs, because they cannot test them. Bearing in mind they don’t have much impact on rats, anyway, I wouldn’t want to risk using them with hogs around – they may not stop the hogs, but they might deter them.
As well as the rat, I have had a cat problem here. I had stopped chasing them away, in the hope that they might put the rat off, but one of them managed to squeeeeze it’s way into the hog feeding box. I have now had another box made with a double bend with the second divider removable for the summer when larger hogs are around. Of course the rat could still get in, but hopefully not the cat. I have heard that rats are not so keen on cat food (not sure whether that is true or not) and so have been leaving kitten biscuits in the new feed box in the hope that the hog will like them and the rat not. (I usually use hog food which cats are not supposed to like – most don’t, but there is always one(!) and, of course, rats like it.) Small amounts of the kitten biscuits have been disappearing (but there are usually some left) and the hog has been seen on the cam entering but, so far, not the rat. Of course the cam isn’t totally reliable and the rat could easily have quickly sneaked in between clips. But, I have also been leaving some of the usual food outside so maybe the rat is content with that. I just hope, as the hog is still visiting, that it actually gets some food, one way or another. If nothing else, it is frequently seen drinking water.
No sign of the rat last night, so fingers crossed. Good luck to the hog there, hope it manages to get some of the food and safely survives until the Spring.