Soil or hydro?
Do u have the money for an aircooled reflector?
Do u have the money for a high CFM outtake fan?
If so then u might be able to squeeze a 400 in there and do a screen. I have a 400 watter with cooltube and 6 inch duct fan along with a 265cfm active air blower and carbon filter in my 2'dx4'wx6.5'h tent and I have trouble keeping my temps at a constant 78 though they never go over 81. Of course as long as you have the airflow then you can always make it work.