Just a random thought, not a suggestion or criticism… I wonder if the flywheel is actually needed.
Obviously, something cheap that breaks or slips between the expensive parts is needed, especially if you hit a rock and it bounces backwards. But I wonder if the motor itself is able sustain the travel speed and generate enough constant torque to eliminate the need for the flywheel.
It is needed for a gas engine because of the torque curve, and to help balance out the torque between the power strokes of the engine cycle. understandably the 5hp motor isn’t as smooth as a 3-phase would be, but I wonder if it is enough.