Alex, I grew up on "tall tales" and believe in them as a part of the rites one passes through in growing up. I have a vast store (well, all right, maybe only half vast) of stories ranging from completely ridiculous to the almost believable.In traditional cultures telling tales (lying) is an art form and an entertainment. I don't think my children suffered from their belief in the Easter Bunny, the Tooth Fairy, or Santa Claus. In fact these have become treasured parts of their childhood.
This is not to say you are wrong in what you have done. Obviously your children have appreciated it. As I see it there is no right or wrong, only different ways to approach the holidays.
Oh, and I love the idea of the kids sleeping under and around the tree. Makes me wish I could institute it for my kids.