Problem is expelling the head caused by the light. If you can keep that and rh I’m sure you can prob make it work. Ideal situation is to have some air exchange though, can you leave a flap open?
I have a SF- 2x4 it depends on the ambient temperature of the surrounding room and what the temperature is inside the tent. If it's low 80;s you good....if it's low 100's you bad....
I too leave the door open quite a bit too because humidity starts to get high in flower