Side light: Clamp light no diffusion, no reflection.
1/30 sec, f/5, ISO-2000
Side light: Clamp light with diffusion and reflection.
1/30 sec, f/5, ISO-2500
Back light: Clamp light no diffusion, no reflection.
1/30 sec, f/5, ISO-800
Back light: Clamp light with diffusion and reflection.
1/30 sec, f/5. ISO-1600
To get these photos I clamped my light to the pantry shelf next to my table. The light was between 1 and 2 feet away from the food. For diffusion I used two layers of tracing paper over my clamp light and for reflection I built a reflector out of cardboard with computer paper taped all over one side. My reflector was as close to the food as it could be without getting in the frame of the shot.
The side light got softer but the back light only marginally so. You need to fill the light more and or diffuse it more to make the back light work.