Rear Mount Camplight

I'm trying to rig up a light on the back of the Disco to help with camping.
I've modified a gutter mount uhf aerial type bracket to fit along the rear gutter near the door. To this I will fit a light and connect it through to the rear cigarette lighter.
I'll leave the bracket on, but take the light off while I'm driving to save any stone damage.
Does anyone have any suggestions to use for the light? I've looked at cheapie driving lights but this will give a harsh pencil beam. I really need a broader softer light e.g. white fog light.
Narva and the like make a "work light" but this is around $90-100. Any cheaper options spring to mind?