I was kind of thinking along the same lines. Just be busy that weekend for some reason or another. Finding something fun to do to distract them would be a great idea. I think the hardest part will be keeping it going though since Thanksgiving is kind of early in Nov this year. Not counting the weekend of Thanksgiving, you'll have 2 whole weekends at home before you leave on the 15th.
It might be worth it to look into getting a tree somewhere... I don't think I'd want to leave the house for a week and a half with a live tree in my living room, regardless what I paid for it. Just too much of a fire hazard to leave it unattended. Maybe see if you can find a decent deal on an artificial tree to use this year.