http://www.cargobikegallery.com/2009/11/76-da-mule.html
When I met the builder in 1994, he claimed that the trike in this link was used to tow his station wagon. Whether that included hills or not was not said but there is no reason to doubt. When I rode it, he had a super low 1:10 first gear - yes... pedal 10 revs and the ATV wheel spins only once.
:)ensen.
