I have a bigger tent (1 x 1 x 2 m), lamp of the same power, extraction fan, passive in-take. I had the same problem (temperature was up to 85 F) along with low humidity (40-45%). I've installed lamp cooling system and bought evaporative cooler, and it solves both my problems. Now temperature is no more than 77 F, usually 74-75 F. The desert cooler is outside of the tent, working on low speed, and I have to switch it off some times.
On the picture you can see a reflector with ducts, you can also notice extraction fan on the ceiling. Ballast is hanging behind the reflector, outside of it. It looks really cheap and awful, I guess you don't want to see it =]