The two fan scenario is crucial if you plan to add additional co2 into the mix. The reason being that you can run your air cooled hoods while the co2 is being dispersed and your fan is not sucking the co2 directly out of the room.
There are a million different scenarios on how to do things, but the cheapest will be:
hang your filter inside the tent and run ducting from the filter into the cooled hoods and have your exhaust fan at the opposite end pulling air out of the tent.
The vortex may be the fan that you might want to go with. I used to have one and loved it.