1 Fan/filter 2 tents

So I was thinking about this to save a bit of money, if I used 2 (2x4) tents, one for veg and one for flower, stuck with 3 plants in flower at any time. Used the veg for a mother/clone.. have the veg tent connected to the flower tent to pull the air.
would I be able to get away with a 6” hyper fan or would I need a 8” hyper fan, to have negative pressure in both? Or would it be a better idea to do a 6” hyper fan in each, and have my filter in the flower tent to eliminate smell for both tents?

Racing basic working knowledge - with air going either direction everything must be the same exact length or shape if there's more than one conduit.

Just do 2 separate smaller systems .