Smart looking hog house and looks a good size too. It is possible that you have three youngsters using your box. They will sometimes share. A lot of the more mature hogs have gone to hibernate by now, so they could be youngsters. But I do wonder if it is possible you may not be seeing them coming out on the camera. I know my boxes have on occasion been used by several different hogs on one night, for naps in between moving on. Sometimes more than one (youngster) at a time. Not sure how your camera works, but with mine, I have found hogs are very clever at doing things between clips. I am often watching in ‘real time’ as well and find that what I have seen isn’t always on the cam. They can be surprisingly nippy when they want to be. Having said that, I sometimes think they like to keep us guessing!
It’s lovely that hogs have been using your box after you went to the trouble of making it. I hope they all have a safe hibernation.