I am venting the new trunk battery in the challenger, but years ago had a 340 duster with trunk battery and cheap boat type plastic battery box, no vent except into the trunk. Ran many years that way.
One evening the drunk neighbor was "parking" his car, and hit my parked Duster. Hit the Duster in the rear... hit it so hard he shoved the car over the curb and thru a fence...no battery problem at all. Eventually sold the car, the new owner worked oil rigs in Alaska, drove the car back and forth many times on the alcan highway, he put thousands of miles on the car and never had any problem.
I imagine there could be a chance of problem in the right accident/circumstances. The gas tank in these E-bodies is not exactly the safest design. For taxi/highway patrol use their cars need changes to the rear of the car to prevent fuel tank related explosions when the cars are hit in the rear at high speed.