In hot weather I always extend the awning as that covers the outside vent for the refer. That's all I do normally that's any different than any other average temp situation.
Some people add a pair of fans up on the roof inside the vent cover to help move air. I haven't yet because I chase cool weather most of my full timing.
I did add an inside the refer fan that so far over 3 years has kept the radiator fins free of frost and the refer cool during summer...that frost used to cause my refer temps to increase to where my beer wasn't cold enough for me. And I didn't like having to defrost once a month like when I was in Florida. So...in went the fan...no more frost:
Refer Fan Installation
You put cold food into a refer you've just turned on to help get it cooler faster...usually 1 gallon jugs of FROZEN water is what people use. 1 in the freezer, two in the refer. So instead of it taking 24 hours to cool down, it only takes 8 to 12 hours. That's not how you cool it down during hot weather though.