I used an apple corer my first couple of times, but the holes were on the small side limiting what one could put in it. I ordered a pineapple corer, link below, from Amazon and am getting ready for my first run with it right now. I am using cream cheese, a touch of shredded cheddar and Spam and then will roll it in olive oil and kosher salt after i cap the ends. I will then wrap it with a couple of slices of bacon, finish it with toothpicks and then try it at about 275 for around 3 hours.
By using the pineapple corer and easily removing the slicing fin I was able to buy larger potatoes and stuff in a good bit more "GOODNESS.". I will be serving it with bacon wrapped marinated skewered chicken tenders and watch and smell the magic as it happens. Cook until almost at temp, and then sear and crisp up the bacon in a frying pan and then WOW! Sorry, I borrowed the picture from another.