Charging battery on the road with portable generator

Has anyone tried charging their battery with a portable generator while driving down the road? You'd probably have to isolate the camper battery from the truck charging system. I carry my Honda 2000 on a rear carrier rack. Thinking that charging for an hour or so between stops would be better than the small amount provided by the truck system. Hair-brained or feasible idea? How would you isolate from the truck charging system?