We live in an age of motor vehicles. Few of us could consider, for safety if nothing else, taking to the roads in a horse drawn vehicle. When the automobile seemed here to stay, caravanners in Europe adapted to the new technology.
The earliest models look essentially like their horse-drawn cousins, just stuck onto a truck chassis. In this era, I suspect they were topping out at 35 mph.
This is the earliest side-door design I have found which changes the dynamics of the interior layout. Note that in the vehicles above, the driver is still fully exposed to the elements. A far cry from our modern experience. Note the “driving coat” worn by the pilot of this beauty.
This style fold down seat/bed is exactly what I had in my first Ford pickup camper. Simple and practical. Maybe these early designs will inspire more modern builders to dive in and get their build on. Keep it simple, keep it light.