My brother is building one in his basement. He's got the front suspension almost done. The frame is next. His will have two seats side by side, with a steering wheel. In the rear he's plugging in his Yamaha V-max! Should be an interesting ride! When I'm too old to hold up a two wheeler I'll either go that route or get a side car. Probably a side car, I don't like the steering wheel part either!
The Morgan would be a lot easier to drive than a sidecar. But they are both relatively dangerous because of the inherent instability of 3 wheels that can't cope with sudden or extreme maneuvers. However if driven/ridden within those limits, they are fine and fun.
For example, there was a kit car once offered, the Fire-Aero, with 2 wheels front and a motorcycle drive train in back that flipped when a popular magazine road tested the thing. Just because it may look like a sports car, that doesn't mean it can handle like one,
Insurance does not matter. Initially the Atom was available as a kit car here in the states, only through a dealership in California, but I believe even that has been shut down due to DOT standards. Don't know anything about the T-Rex, but if they ever build one of the Atom's for the US, I want one.
I saw a T-rex in person on my way home from Buelltoberfest. I'm surprised by the price tag, I thought it would cost half what it does based on what I saw. Looked like a tech school final project involving a wrecked 'Busa.
The KTM X-Bow is available in the US now as a kit car, just drop in an Audi V8 (sold separately)
Here is something like my brother is building. The front suspension is C4 Corvette with the coil over conversion. My brother's will have a V-Max plugged into the back. Looks like fun even if it doesn't lean in the corners!