Graupner (I think) and Astro Flight in the past have had pusher motor/props on glider wing configuration airplanes.

I had one of the Graupner motors and the props were a low speed design and were spring loaded to fold and trail behind the motor pod/wing without power.

The pod was essentially the same diameter as the motor and was faired into the wing. It extended a few inches aft of the trailing edge. It worked well.