A) have exposed 2" vent pipe inside of bathroom showing.
B) have vent in wall but elbow it out into room up about 6 feet off the ground to get it around roof rafters.
.
I am in the same boat with a bathroom reno.
As Terry once said about the plumbing in my old house,
there is nothing that is right here
Locally, I can use 1.5 for the vent portion, can you use 1.5 for the vertical section of the vent in NH?
Maybe you should consider building a small box around the vent pipe.
I will have to do the same. It is impossible to add a vent to my bathroom (nothing was vented in house) the way the walls were built, so when I gut the bathroom, I will have the vent line run vertical inside the wall to the ceiling and then horizontally out of the bathroom in a small box.
Pain in the a$$ but there appears to be no other way and it has to be vented. Sounds like the same deal for you.
Now if only they invented Wiremold for plumbing vent lines