This is one of my kick scooters.
https://endless-sphere.com/forums/viewt ... 35&t=83830
It will do 24 miles on a charge and tops out at 43mph and accelerates like my Golf GTI. That's overkill for your wife, so just build yours less powerful. It weighs 70 pounds so that might be a bit heavy for her, but I was looking for good performance and you don't need what I have for your wife.
I think for everything I have $600 into it.