1600 watt venting

So i have switched my grow rooms around to a much smaller room (7x8.5 insteal of 8x12) switched to aircooled hoods and upgraded my 400 to a 600 my hoods have 8 inch openings and i have an 8 inch fan and tubing. I would like to run the light ventalation as sealed but there is no openings besides the window ane the door. I cannot suck air or exhaust from outside for cooling as it will frost at night in about a month and i would have massive condensation issues. Is my only option to suck and filter air from my room and exhaust it somewhere in the attic? I prefer to run a filter on both ends of my ventalation if i do it this way but is one 8 inch fan enough to keep temps incheck setup this way? Or will i stil need to use my window mount ac till daytime highs are below 20c...nn thanks for reading my ramble

My setup is similar. 3 600w lights, I have tried so many different variations on what to do, I finally ended up sawing a hole in the floor and pulling air from underneath the house, push through all lights and then vent into another room through the wall. Keep as few turns as possible, and as little back pressure as possible. Remember that only pushing not sucking will lower light temps.