Cool stuff GH. Looking forward to seeing where you go with this.
Related side note, I always thought the bicycle BB was over complicated. Works great and is amazing but could be done better with the parts and the like your suggesting. 3pc where the cranks just slide in and are locked with a set screw. If you need wider or shorter shaft, just swap it out. Could make your own with a drill press and cut off saw. Would make it a snap to add engine powered freewheel.