Comet Skyray

I want to build an Elec. Duct. Fan model of the Douglass Skyray using the Comet (of Chicago) plan as an example. It is of 15 1/2 inch wingspan, for kit Y-9, and already has a flat bottom airfoil.

Considering the weight of R/C receiver, servos, batteries and a Kress EDF (like an RK-709E unit), how much should I increase the wing area in order to convert this Comet Skyray glider in to a powered unit? I have not made an estimate as to wing area or loading as per original plan yet.

How big of a tailcone and inlet ought to be required too?
Or, has this been done before, and a plan made up then?

Wm.