Aerodynamics are at least as bad as weight when it comes to trailers iirc. And there are at least leisure trailers that come with battery packs in them. The Lig

Aerodynamics are at least as bad as weight when it comes to trailers iirc. And there are at least leisure trailers that come with battery packs in them. The Lightship and Boulder come to mind for instance. I suspect it's a matter of time for more utility trailers, if it's not already a thing. Batteries are expensive though.