Help with high temperature

You need gas exchange unless you are adding co2 artificially. Otherwise, whether 4x2 or 4x8 it'll just fill up with a higher amount of O2 and less CO2 than normal. Small plants may be okay, but at some point i'd assume bigger plants will draw down co2 if not enough air is refreshed. Even the 'lung room' - whatever encompasses the tent or tents. So double tenting is as useful as double bagging a condom. If you can keep CO2 up and not have too much RH, a sealed room is doable, but otherwise it's a bad idea.