The best way to travel across South America for a long way vacation is by a mobile house. It should have all the possible comforts to sustain a family, some beds, have a bathroom, were everyone should do all its biological waste, a kitchen were they will prepare food every day on the trip. Kitchen is important, because food in some countries is very expensive. Wireless internet so we can connect to the GPS in case we get lost. Also have a big mirror, so we can appreciate the view along. And finally, it should run in diesel, because it last long, the mobile have to be in good conditions for travel.