You would need to check with the local inspector, I think you can in King County.
If you have other vents in the home, you could get by with a 2" vent for that bathroom set through the roof.
A 2" is pretty easy to flash. The last time I did that for a 2" vent run from the basement through the overhang in Seattle, I roped myself off while on the roof.
I used my harness for mountain climbing.