That is going to be one savage looking vignette (sp?). I can't wait to see the final piece.
On a side note: As I was looking through the model picts (your students are doing an excellant job) I started wondering what the models would look like with a comcieved background. For example the headless horsemen. What would it look like against a photo/painting of a eerily lit night wood scene? There's some fun to be had there as well as composition/perspective lessons.
3d modelling is an option
a true mental excercise in frusrtation