Definitive Answer: D5 an Option for Picture Backdrop?

Hello,
i just need a clear answer on the following:

Modeling onto a picture (Backdrop/ Wallpaper) in rhino is no problem, i just want to render in D5.

Now i found no possibility to make that picture a backdrop in D5 Render so i can have it as a backround. I also can not export JUST THE RENDERED MODEL from D5 so i can put it in the picture via Photoshop. No environment, sky, ground plane.

Is this really It? Is there really no Option to get a Picture as a Backround on Something i made in Rhino with D5? Whenever i include D5 it is for nothing?

If somebody could clear this up it would be much appreciated.

Thanks and regards