Whether or now you get tank "fumes" through the roof vent depends on the placement of the vent relative to the tank vents ...in our coach, the only time we have noticed black tank odors in the coach is when we are driving with the rear roof vent open. We've never noticed tank odors coming in the roof vents when parked ...since the roof vents blow air OUT of the coach rather than sucking air in, if odors do come in the roof vent that should be easily resolved by just turning on the vent fan and opening a window so air can be pulled in the window and out the roof vent.
I've wondered about the 360 tank vents too, and have seen some other similar products.
Paul (KE5LXU) ...was fulltimin', now parttimin'
'03 Winnebago UA 40e / '05 Honda Odyssey toad