A rig's roof broiling in direct sunlight will absorb "x" BTUs of direct solar radiation. If you can figure out a way to shade it while allowing airflow between the shade and roof top, it definitely will make a significant difference in the balance of heat extraction versus input.
And remember it takes lots of energy to dehumidify air. My A/Cs spend the first half hour of operation reducing humidity. The water condensation of the evaporator coils contains all of the "cooling ability" of the unit. How much energy does it take to precipitate water from air? A lot. It is felt in the form of reduced cooling. It may pay to investigate the practicality of using a LARGE capacity dehumidifier if your inside humidity is 60% or above at ANY temperature. Changing the temperature of water (vapor) takes a lot of energy.
