SGR, iIread your proposal to dent the wagons with interest. I did this many years back with some LGB versions of these. It was very succesful (sadly they have been sold so cannot post any pics) but I respectfully suggest that you treat the Binnies with extreme caution, if memory serves the plastic is a lot thiner. So gently gently.
My way was to hold the iron as close to the edge as possible without touching it, when the plastic became pliable I used a skrewdriver to wedge bangs and scrapes into the pliable plastic. Hope this helps and good luck.
JonD