I don't know the answer to that question. I can give an opinion.
I have been in the school bus business and have been fixing them for over 47 years. I've seen the best and the worst. I remember when my dad started in the business. He rolled the chassis out from under the body and replaced the chassis to get another service life out of the body of the bus. That can't happen today. Manufacturers have reduced the wall thickness of the bodies and they've made the buses lighter. The chassis are lighter. It's interesting after a few years on the road, to put 63 high school students in a school bus and go out on Foxtrap Access Road and look in the mirror and watch the seats of the bus doing this as the bus is going down the road. The body of the bus today is made so light that it can't take the punishment that it did back in the 1950s and 1960s.
I can't see that it's possible to retrofit a school bus.