While searching for more details on the Lunartic, found this Dyson Design Award nominee and it has some promise. A convertible cargo bike with electric assist:
This is a utility pedal-assisted electric bicycle – tricycle that can be ridden like two-wheeler or like a three-wheeler depending on the intended use. When one needs to carry a heavy load, then the rear wheel can be split and transformed into a three-wheeler with a loading surface (up to 150 litres and up to 40 kg). It is bigger than some trunks of small city cars, yet big enough to carry a full load of shopping cart. The BIQUATTRO has a specially built suspension that allows the bike to tilt to the left and to the right for steering. This permits the rear wheels, which are extremely narrow to each other, to tilt independently ensuring a better steering performance and user experience (it feels like a two wheeler, but it is more stable).