Custom snow plow part/Christmas layout.

I am toying with the idea of stringing all of the coaches together and using a set of 10 LED's that run on two AA and fitting a rear caboose or flatbed with a tarp like housing to cover. Not sure how that may work though. I like the one super did with the red coaches.

The second to last car on the Flying Kipper is carrying a item covered in a tarp. I would take advantage of an area like that to hide a battery. For a passenger train, take a van, for example this blue mail car. Scroll down to the products.
http://thomastrackmaster.wikia.com/wiki/Dodge