Seems like you have a range of options and should maybe look at what's out there first - ie, on the one hand you have various somewhat conventional bicycles with frames designed to hold a chain drive in place while hinging, on the other you have something like the Hoppley Circus Bike that is essentially a pair of unicycles mated by a rectangular frame with a head tube on each end.
If you go direct drive, keep in mind you'll probably end up with a tiny gear ratio especially if you use smaller wheels. And unless you start with a drift trike (vs unicycle) hub you'll also be fixed gear - which can enable a lot but changes the approach to riding. In those configurations you'll probably want short cranks, too - say 125mm, even 150's are likely to feel like pedaling air to no effect.
Last edited by UniChris; 02-28-20 at 11:04 AM.