Welcome to the Forum! That’s great to hear you are excited to have hogs there.
Ideally it’s better to have separate houses for feeding and, hopefully, hibernating. And not to keep the food too close to a nesting box. But the hogs will sometimes take over a hog feeding box/house to build a nest in. It’s happened here several times! The first time I had to get a new feeding box. This year that feeding box is being used for hibernation! So you might need another box/house too!
But the thing to remember is that a hog box is just a structure within which the hogs can build a hibernating nest – so materials are as important as the actual box. Most natural materials are medium sized leaves, long grasses, etc. So if you want to remove leaves from your lawn just rake them into the borders so they are still available for the hogs. Hogs are known to move nests during hibernation time, so materials left available all winter are helpful for them.
I do get mice here, but they don’t normally have much impact on the food. (and any cats that visit, hoping to get some hog food, seem to totally ignore them!) Are you sure you don’t have a rat as well. They will take cat/kitten biscuits and cache them elsewhere. Mice will cache as well but may not be so keen on cat biscuits and here, mice haven’t ever taken all the food.
The hog may not have visited because it has started to hibernate elsewhere, but if it has you may still get another one to use your box. Good luck.