I have not towed across the Key Bridge in the left lane. I have only done it in the right lane. I have towed a few times through the Baltimore Harbor Tunnel in the left lane with no issues. I did that because, with it being dark in there, it was easier for me to judge how close I was to the wall by having it right next to me and not the passenger side. I don't remember any signs at either place saying I couldn't be in the left lane.
2017 JayFlight 28BHBE
2014 JayFlight Swift 264BH (Sold)
2007 GMC 2500 Sierra Classic Crew Cab LBZ Duramax / 6spd Allison