How to motor test the Lamborghini Sian (42115)

I am about to begin building the Lamborghini Sian, and at an intermediate build stage I would like to motor-test the Sian's gearbox and V12 pistons, but without modifying the final model. What is the best way to conduct such a test, and with which Lego motors and battery boxes? Here is what I am anticipating, but please correct or improve any of my assumptions. Once I have the V12 engine block installed, the 8-speed sequential gearbox assembled, but while the drivetrain is exposed and no...