My friend Bob Winkler had a boom tender and an unused flat car on his layout for some time. No work train however and no wrecker. I'd had this crane model among my collection for some time. It is essentially the crane offered by Tru-Scale in the 1950's and by several other manufacturer over the years. I decided to build Wink a work train for his Central Maryland short line RR. I added sides made from scale strip wood to the flat car. Added rail, barrels, chain and other details to both the flat car and the boom tender. The whole ensemble was weathered with chalks. Not sure I'm a big fan of chalks although perhaps I might have had greater success if I'd used Pan Pastels.
The boom of the wrecker has to face the flat car as it's too long for the boom tender and hits the cabin.