If anyone is interested, I have scale drawings I made for that 32' "New Moon" trailer, built by Red Man Industries in 1953. I built the model in styrene and used model airplane wheels under it. Since the trailer was shown in the movie with its blinds drawn, I printed some Veneitian blinds on paper and glued them behind clear styrene glazing.
The car is a '54 Mercury "Sun Valley" convertible. It was made in Argentina some time ago. Its color was fairly close to the '53 Mercury "Sun Valley" and the '53 Lincoln "Capri" convertible used in the movie. I could not find a die cast '53 Mercury convertible, so a '54 had to do. The trailer and car carry the accurate California tags numbers of their prototypes in the movie.
The Lincoln did most of the heavy hauling in the movie flimed in Yosemite National Park and shot at a distance. The Merc was used for the close-ups and manouvering shots. The figures in the model are modified Circus Craft made to resemble that famous couple. She is even holding a map - upside down, of course!