Fermentation is done so temperature is not a worry any more for adding off flavors. CO2 will off gas faster as the beer warms. Less CO2 off gassing, during dry hopping, will keep more of the hop aromas in the beer.
You can set the fermentor in a tub of water to keep it under the high ambient temperatures you will be experiencing, but temperature swings of the tub water will not be a problem either. Experiment with one or two ice filled soda bottles each day for a comfortable temperature.
I would be nervous about the beer reaching 80° during dry hopping, even if it would not be detrimental to the beer.