Have you considered moving the riding position to a more traditional Penny farthing style? That’d put more of your body weight on the large wheel rather than little one. You wouldn’t have as much traction, but it would put less load through the drive axle and allow to weigh less (thereby giving better efficiency) and the rider would have a better ride since most of their weight would be on the giant wheel. It wouldn’t be as dangerous as those old school Penny farthings since the wheel could be much smaller.

If you needed more traction, you could just lean back a bit to load up the rear wheel more.