Don't worry about it.
Yes, black will hold the heat a bit more than white or even red but it shouldn't have any noticable effect on your car's cooling ability.
To eliminate cooling problems, be sure you're running a well-functioning cooling system; clean radiator (sized properly), good hoses, high-functioning fan and water pump, 180 or 192 degree thermostat, non-slipping serpentine belt, 60/40 water/coolant mixture and a bottle of Water Wetter and you should be fine, even on those hot Texas days.
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