Those temps aren't way too high, the optimum is 76-78 so you are slightly above the ideal range but it's not going to hurt them.
What I would suggest is that because it is hot in there, and you have no ventilation (oscillating fans don't count, they just move the hot air around) you have your lights too far above the plants and they are stretching from lack of light.
We need to know a lot more about your setup if you want any kind of useful advice, answer the questions I asked you originally and we should be able to work something out.
Do you have a thermometer with a max/min storage feature? If not get one, they cost next to fuck all and without one you have no idea of the temperature variation when you aren't there.
What kind of co2 injection are you using? A diy with yeast or whatever, or is it an actual co2 controller which regulates the ppm level in the air? There's very little to be gained from giving plants co2 unless you can monitor and regulate the amount they receive, and even then it won't do much unless other environmental conditions are close to optimum levels.
If you insist on keeping the co2 and don't want to extract the air out of the room, get a pair of air cooled hoods, or even cooltubes if you must, and make a cool air inlet at one end of the room, with ducting running from there to the first light. Go from there to the second light, then have around a 300cfm fan pull air across the lights and blow it outside, that should keep your temps down, and allow you to get the lights in close to the plants.
