My advice would be to get some traction trucks with motors and run the cars as MU's controlled from #12, which will merely put on a good show with steam, smoke, whistling, etc., like Grand Canyon Ry. Since the fuel usage for #12 will drop at least 50%, the geneator set can reside in #12's tender.
Skip Luke
Switchman (ret): Grand Canyon Railway;
Engineer (ret): Georgetown Loop RR Inc., Sumpter Valley Ry., Monticello & Sangamon Valley;
Dispatcher(ret): Illinois Central, White Pass & Yukon, Burlington Northern Ry.
Mariner, Musician, Miner