If I do shoot better it is because of the lighting and back ground allows me to see a bit better.
I have that same problem. What I did to help me a bit was to put a weight on the target to angle it upwards so it would reflect the bright sky instead of reflecting the dark grass.
I used to not be able to see that 8 x 12" target at 300 yards when the sun was high or behind the target, no mater what color I panted it; now I can see it anytime of day.
It also helps to have the chains in front, it tilts even more.
Great shooting BTW.