I hadn't thought through that part, I just have an unused utility pole. I also have an air compressor tank that I could paint black and wrap a fresnel lens or two around. The weight would keep it on the ground where it would get (a little?) less light.
The opposite case is where you use the fresnel lens to mimic sunlight:
hackaday.com/2019/08/17/great-artificial-daylight-via-broken-tvs/