Unless you are going to devote 6 hours a day from now until Thanksgiving eve to get this layout up and running, forget it. Too much work and too little time. Now, if you can round up 3-4 experienced train friends to help you out, you have a chance.
Sorry to say, but you should have started this ambitious project on the 4th of July.
My BEST advice... settle for a simple oval, paint your board white, get some fake snow from Hobby Lobby. You will be less stressed and she will be just as impressed.
Good Luck my friend.