Electric Motors on Trailers

I know this concept has been out there for a while, but to my knowledge has not yet been discussed on this forum. What do you think about the idea of electric motors on trailers to extend the driving range of an EV towing a trailer? I find it fascinating how the RV industry is now actively looking for ways to adapt to the evolving EV towing future. What will be the technical, cost-related and practical challenges?