Ok, I might sound a bit greedy, selfish, and stingy here, but why are you basically punishing your son for having a birthday 2 days before Christmas? Would you have the same kind of "no presents" party if his birthday was any other time of the year? Most of the "fun" of a kids birthday is opening presents. Why are you taking that joy and excitement away from him?
I have an aunt whose birthday is the 25th, and it always seemed like she got "combo" presents. I always thought to myself, why should her birthday be any less important (because yes, Christmas does trump the excitement of birthdays) than any other persons special day any other day of the year. Then I would think about my dad whose bday is June 23, almost exactly 6 months from Christmas, and how it was basically about the perfect day for a birthday, 6 months between the two.
Why don't you have his party earlier in the month of December, so it is not right in the middle of the hubbub of the holiday time frame? Then on his actual day, you could bring cupcakes to his preschool class.
Or, you could let him celebrate his half birthday and have a party in the summer. I know a teacher who does this for her students who have summer birthdays. Since their 1/2 birthday falls during the school year, that is the day they can bring cupcakes, etc.
I would definitely not go with the moon walk. One child at a time, how boring can that be...for the one child jumping and for the others who have to wait for what is an eternity in their minds time frame. Please!!!