Welcome to Hedgehog Street.
Sorry to hear the hogs didn’t use your old box. I have one box which a hoglet made a nest in this winter (only for short stays – it decided not to hibernate) but I had had it quite a few years previously.
When you have been on Hedgehog Street a bit longer you will find that stopping cats eating the hog food is a perennial problem. I used to use the box the nest was built in for feeding, which I thought was cat proof ….. wrong. The cat got in there the day before the hoglet started building the nest. A friend quickly made me another feeding box with two partitions so that it had to turn sharp left, sharp right, sharp left. I thought a cat really couldn’t get in there ….. wrong again. I put a half brick in the first corner and to date, although a cat has attempted and got halfway in, it hasn’t succeded …. yet. Luckily the hedgehog hasn’t found it a problem.
So, I’m not sure whether you will be able to make a hogilo cat proof. The only thing I did wonder though, is have you pegged it down so that the cat can’t lift it up? A cat might find it more difficult to get through the tunnel if you have. I just looped a bit of garden wire over the top of the tunnel part and pegged it down with whatever I could find. I have seen tent pegs suggested. (It is a good idea – to deter predators, too) If you have already tried that, maybe you could try to make the tunnel longer somehow (?) But, really I would think some other arrangement would be better for feeding and hope that a hog uses the hogilo for nesting, either Summer or hibernation. I think one answer might be not to have whatever you use for feeding too high, so that the hog can get in but it’s not so easy for a cat. I remember someone used one of those clear plastic under bed boxes, quite successfully.
There are some kinds of hedgehog food which cats aren’t supposed to like. I normally use ‘I Love Hedgehogs’ food which has recently improved its recipe. Most cats didn’t like the old version, but one did. I haven’t seen any cats eating the new version yet. There are other varieties which cats aren’t supposed to like. I have been using kitten biscuits recently in the hope that any rats wouldn’t like them so much.
Although it seems as if the hogs should still be hibernating, they do apparently wake up sometimes during hibernation and might welcome some food and especially water. I have also heard this year that some hogs have come out of hibernation early. It has been quite strange weather with some very mild spells. So it isn’t a bad idea to put some food and water out in case.