I do like leaning trikes and other cargo bikes, but not for ease of construction.
I like the idea of using a Nuvinci hub gear with a motor. So that it is easy to match the pedaling with the motor speed.
|High speed high voltage LightningRods motor, moped tires,|
boxes front and rear, vertical sitting position, and disc brakes,
and most important a two stage gear box driving the left side of the wheel.