I just hung my 1800 and am about to start framing the closet and this is a very timely post. I'm not sure though what you are saying. It seems you are venting the dust outside and are observing dust in the air outside. Correct? If so I don't understand your concern, isn't that the result you were looking for when venting outside? So are you now going to add filters and vent through them inside? What am I missing here?
I currently have the nano filters hooked up and the cyclone in a closet that vents outside and everything is working well. I had hoped (in my early testing) that the venting outside without filters would not be visible dust. I did not want to have it seen by next door. The dust I did see was so fine that you would have to be looking for it.
If you are going with no filters you better get a dylos meter as I was shocked to find the fine dust got back in the shop.