Thanks!

If your looking to soar power off, the fan enclose will generate a lot of drag on the order of badminton birdie (I would think). First thing that springs to mind is Rutan's dethremalizing re-entry system for his Space Ship One. I would think you need to have your intake for the DF enclosed and puling the air in through a NACA style intake that is in the top of the wing, so with power off it isn't creating a lot of drag like it would having the df unit hanging out in the back. With power on a area of low pressure occurs on top of the wing. Is that a bad thing? I also wonder about any blanketing or interactions the control surfaces my cause relative to the df unit intake.

As an aside... Have you noticed that in many of today's experimental designs you see a lot of the Star Trek type of pods for the fans on them?

One interesting concept you may want to look at...
With a DF you have the option of incorporating vectored thrust. I added a rudder to the exit duct of a Miglet DF flying wing, you could get that thing to fly knife edge. Add elevon function as well and it gets "entertaining".

Yet another question. Those 3 fins are going to generate a lot of interference drag with the duct tube won't they? All of those junctions with the fuselage/duct, do you need that side area?