Here is a rendering from back in 2004.
The Stowaway II offered the elongation which would allow boat-tailing,and there would be the utility of additional cargo space without resorting to a roof rack system.
Earlier European designs had retractable wheels which would allow the tail to be slipped out of the receiver and rolled away without any lifting involved.
I'd gone through an advanced composites course at ABARIS and knew that a composite structure could be extremely light,since this is an all-compound surface and benefits from 'egging'.
A thermo-formed plastic structure would also be doable.
All light-metal,likewise.
A passenger side window would be beneficial when backing,as the 'C-pillar' would be enormous.
Or a camera system as is common now.
I won't be going for a patent,so feel free to use it if it can help.
The Koenig/Kamm K-form was predicated on a 50% frontal area wake.So this would be the recommendation for a 'practical' length.