 The New Moon trailers, produced by The Redman Trailer Co. (as per  original sales brochures & in viewing the actual 1953 models),  didnt come with a "sunken living room" as was highlighted in the  film. This was done to add a reason for Desi Arnaz (qv)s  character to take his pratfall when first entering the trailer. You  can see that the floor of the kitchen is flat with the living room  floor if you look closely when he opens the door for the first time  at the trailer show, as this was simply a regular production coach  in the shot. The interior shots had a "dropped" section in the  living room area and you can see that the vent windows are much  further from the ceiling than they would be as seen from the  exterior. New Moon trailers also had a furnace in the corner between  the front door and the kitchen cabinet. It is assumed this was  removed from the interior mock up for aesthetic reasons.