Yep. We have seen journals here where the grower would have their flexible duct hose, fan & filter equipment outside of a tent. The only part that was still in the tent would be a couple of inches of the duct hose that went through the porthole.
And then there are those who have mounted the hose, fan and the filter inside the tent and the filtered air is discharged back into the tent. Nothing that is part of the air filtering is outside.