PUT the dog in the trailer open the windows and be done with it. Dogs and humans survived well before A/C.
If your dog cannot survive a little heat then leave it home.
To an extent I agree about the dog surviving heat, but if it's really hot and no breeze it could be an issue. To add on to darsben's comments, if you have a/c and a genny you could run that while in a parking lot. If not, look for some battery operated fans that you can run if you have no power. Park in the shade if possible. Another thought is to do take-out of some sort and then find a park to eat in or eat in the trailer with the pup.
