Why not develop an axel with an integrated motor? It’d be easily scaled to any vehicle with a solid rear axle. Fill the engine bay with batteries… It seems like an easy approach to get a widely applicable EV conversion kit. Offer a few widths and diameter axles… Is it bad to have the motor in an unsprung position?I see hub motors, so I think not. I guess air conditioning would be another thing.
There would also be some issues with the wheel flange if you want it to match the other axle and the brakes if you want them to continue to work.
But I think the biggest problem would be the the manufacturer worrying about you and me welding it badly and them getting a share of the blame when it comes loose on the highway and takes out a bus full of nuns and orphans.