[flybouy]

The folks at the 2 mentioned tunnels on I 95 and I 895 in Baltimore are Maryland Toll Facilities, not Balt. City entity's. They are patrolled my Maryland Toll Facilities Police. There are "truck check posts" at each portal that used to be maned by MTFP officers.
Many decades ago they replaced the officers at the checkpoints with private contractors. After that personnel change the ban on lpg tanks were no longer enforced or more accurately "reported" so they don't pull over RVs unless they trip a sensor (overnight).

With that being said, if you are pulled over for any reason, or involved in an accident, then the likelihood of being charged for "violating a tunnel restriction" is very high.

I know this as accurate because my best friend was a MTF LEO as is out nephew's wife.

There is a tunnel in Norfolk, VA that will make you pull over and turn off the valves before entering the tunnel.