Applying the depth map to your render with a single color isn't going to cut it to give the best illusion of depth and distance.
So let's read about what painter and drawers have to say on the topic with these two tutorials :
If you've read the tutorials, you've already guessed that I'm going to treat my body as a landscape, receding in the distance.
The landscape picture will be your reference for this exercise. Landscape, body. Depth. Body, landscape. Size.
Ready ?
I don't know. Yet.
There are an infinite ways of doing this, which I'll likely put here but... there's no magic recipe other than experimentation, and I'm still experimenting.
BUT
If you want to see and try what techniques I've used for this picture,
download the .psd and try it for yourself !