>>28511577It looks like he was more concerned with making it look like a freight train than he was with making it practical. I think that a water recycler like a Rankine cycle or similar if you weren't concerned with looking like a choo choo train would have much better range.
A triple expansion with a vacuum cycle for the final piston in place of the turbine would be an option that would allow you to use an atmosphere pressure radiator and be pretty safe in use, but it would also look more like the lovechild of a Gold Wing and an HVAC system than an old timey freight train.