You could get a Styrofoam ice chest, cheap small fan, some 4" ducting, and a roll of duct tape. cut a hole in the lid for the fan to face down and then a hole in one of the sides for the ducting into your tent. put ice in the chest and turn the fan on. should bring it down a couple degrees.
I know this is a really old thread but. . . . . . . I would suggest not using plastic bottles, a glass hooter is way better not only are you not smoking plastic but you can collect really good resin from knife hits.