This doesn't answer the OP's question but an option for gondola side distortion is available for those who cast their own gondolas.
Resin is off course a liquid when poured into the mold and within time it morphs into a solidified casting (which we have been purchasing for decades now). Along the way to being a solid casting, the urethane passes through a range of hardness from liquid to pure solid.
I experimented on a mold from an HO WP Greenville built 29' coil steel gondola side and got some promising results. While still "green" in the mold, picking on the sides with a somewhat pointed, blunt object, outward dents were created. One thing that I discovered was while still in the mold, the distressed green castings tended to revert back to un-dented. The most serious distresses were from de-molding the sides and doing the pointing with the pointed/blunt object while the green casting was on a piece of foam board.
We whom are older than 40 years remember the model presses suggestions of using heated soldering irons from the inside of plastic gondolas to get the dents. Problem was, the resulting dents did not scale well and to me the results looked forced and not very effective. The resin dents, however showed some rather realistic effects.
With all of the YouTube videos offering intros to home resin casting tutorials, and with the readily availability of resins and RTVs, climb on in....the weather is fine!