Thanks for all the ideas.
I returned the MiniPRO to Amazon and will sell my More4Mini handlebars on eBay.
Meanwhile, I bought a used Airwheel S5 on eBay.
See it here:
http://www.airwheel.net/home/product/s5
It has 16-inch wheels vs. the 10-inch wheels on the MiniPRO.
It's a heavier, stronger machine that I believe will be more forgiving on uneven surfaces. If y'all would like, I'll report back after it arrives and I ride it a couple of times.
It's exciting. After years of relative stagnation, there's a lot happening in the electric scooter world.