From your photo it appears that the engineering and design are indeed , top-notch, however the weight will likely make it a perfect candidate for an EZ-GO or CLUBCAR and not for a bicycle powered by just one human.

It is a very cool design. I'd imagine that if you could design it to have a some "train like coupling" where you could connect a "train" of two or three of these (exact clones of your proto-type design etc.) behind a four wheeled, battery powered (electric) EZ-GO or CLUBCAR golf car. That would be an excellent pracical use for your well-built prototype. I think that you will find that though your design is just too heavy in its current configuration to be practical for use with any bicycle.
You might wish to see and essentially copy or acquire one of the old ancient Rickshaw type cab bicycles that were everywhere in Vietnam and are still seen in India and sometimes among some of the destinations that contestants on the active television game show, "THE AMAZING RACE" visit during their travels during the competition.