The transmission was extremely noisy for its 1st 20 miles, despite lubrication & the sound damper.  Despite the noise, the efficiency was a record high of 240mAh/mile empty.  2200kV is a better speed than 2400kV.  The hall effect sensor worked without any firmware changes.  It actually manetaned the same speed going downhill.  There's no brake modulation, so it would have to always deliver the minimum power rather than brake.

A 14 mile drive with 4.5 miles at 10mph & the heavy speaker pulled it up to 300mAh/mile.  The speaker at 6mph only pulled 270mAh.  Drove at high speed to try to break in the transmission & make it quieter, but it made no difference.  The latest theory is the motor is making the noise.

The slightly enlarged cargo compartment was a huge improvement.  There's definitely incentive to upgrade the old vehicle.  Another idea gaining traction is a return to trying to make the handle removable.  Removing the tape & relying on the stiffness of the coroplastic to keep it on was a failure.  

A hose clamp could go on the handle.

https://www.walmart.com/ip/10-Constant-Tension-Band-Hose-Clamps-5-8-23-32/123944532

They're expensive, too tight, & would scratch the carbon fiber.

There's wrapping rubber bands on the handle.  They would be too lose.

There's cutting a notch in the plastic & adding a key to the handle.  The coroplastic is too soft to retain the notch shape.  It would just become a larger hole for the handle to slide through.

There's augmenting the handle with a big rubber band.  It would be soft enough to not crush the plastic, yet have enough tension to keep the sides in.

The leading idea was simply augmenting the handle with string to pull the coroplastic in.  It would be a pain to remove, but it would work.  The string could use a fastener or a simple shoelace knot.

The string idea worked quite well.  There are points of wear, like the coroplastic bending, the tape giving way, & the ends of carbon fiber delaminating.  This allowed the largest single items to be transported.