That's what I was trying to say. Even 2 sets of leds at each end with soften the hot spot. You what to aim for somewhere between 18" to 30" (36" max) off the canopy and the taller your light the shorter the distance needs to be. @ 500 watts ( 30 watts per square foot) that light needs to cover a 4'x4' area. If you run it @ 300 watts it can cover a 3'x3' much more effectively. When I use mine, I only run it around 250w or less.
Set up you light 2' off the floor and let us know what the readings are 2' from center, I will bet it isn't over 800. All those reflectors that you have available, are designed to be 6'-50' in the air. Very few are design for 18" to 30" and even coverage.