I don't think you have to eat a ton over maintenance, but the exact number eludes me also. I went all out during my cut. When you sleep, your body is in "fat loss mode" for lack of better terminology. Not exactly sure why your numbers move so much, you aren't losing and gaining 10 pounds everyday. It may be a trick of the scale. Speaking of which, the scale is a good tool but I would rely more on what the mirror says and how your body feels. You have to listen and respond to it and you will make the gains you are looking for.
Leaders are made, they are not born. They are made by hard effort, which is the price which all of us must pay to achieve any goal that is worthwhile. - Vince Lombardi