I have a bathroom that I am finishing in my house and have no where to run a vent other than down through the floor and out under a porch. Is this an ok solution in any circumstance? all other directions take me into a finished space some kind.

Thought about placing an inline fan remotely in the basement below the bathroom.

I would have the vent on the ceiling and be running the ductwork down through an inside wall to the basement and then out through the header board to the exterior. Total run of piping would be about 20' - 25', at the most.