Donut Spare for 2017 Prius Prime?

I know people are concerned about mini-spare tires possibly not being able to handle the weight of the BIG battery in the Prime Advanced. I used to build Radial Mini-Spares at Continental General Tire and the only thing lacking in these tires is the tread. The mini-spare tires have an innerliner which makes it tubeless. Four plies, which makes the tire sturdy, compared to the 2-ply standard sized tires. I don’t know exactly what the weight capacity is, but I would think it would handle quite a load, but not for very far with the very thin tread that touches the pavement.