There were few RV's back in the '50's. Except for a few years in the mid-'60's, sales remained flat in that decade too. They really took off in the 1970's and that's when I remember seeing them on the roads in greater numbers. Anyone who remembers traveling with one in the '50's had an experience few others had.
I remember early motels from the '50's when the only chain was Holiday Inn and all other motels had character, some not such good character. There were motor courts as well as motels but they were the same. Magic fingers was everywhere and you had to put a quarter in the TV coin box for 30 minutes of TV—sometimes the timer was fast and would cut off the end of the program. When you consider that 25¢ in 1950
equals $2.20 today, you can understand why my father didn't want to watch much TV.
It wasn't RV's that were slowing people up on the 2 lane highways of that day, it was 18 wheelers. There were few 4 lane highways—the interstate system hadn't been started yet. Travel on busy highways meant knowing how to pass and most drivers knew how to do it. Most of the day was a few miles of fast driving and then catching up to a line of cars behind a slow truck. Now it seems most driving is on 4 lane highways and few people know how to pass anyone on a 2 laner. Most large trucks now are on 4 lane highways and you are more likely to see RV's on 2 laners than trucks.
Making a cross country trip then was a really big deal. My father would have the entire car checked over because cars broke down a lot, needed brake jobs and new tires frequently. I can imagine towing a trailer cross country was an even bigger deal and RV campgrounds must have been pretty primitive by today's standards.