[Zeke]

I have been casually watching these for a couple of years. Currently have 5 bicycles to cut apart for my first pedal 4-wheeler. Putting anything but an electric motor on it and you have DMV and insurance mandates. I will be going electric after the pedal prototype is debugged.

I'm looking at mini construction with 12" spoked wheels in front. No body to add weight. It's all cool to look 1920's, but it gets expensive and impractical. I mean what is the point? The point is to experience movement on wheels close to the ground.

That's absolutely the entire attraction. If you want high efficiency, ride a real bike, recumbent or conventional.
Low CG is fun.