It seems only natural that evangelical ministers would take to the caravan as a way to bring the Gospel to the people. Christianity is a missionary religion after all. The caravan served as a sort of home base for missionaries and a vicarage for ministers, even being outfitted with a harmonium (pump organ) in some cases.
Anyway, here’s another aspect of the caravan life we don’t often see.
Finally, the FORTS. A concept of the Salvation Army to travel the countryside, gathering pledges of abstinence and converting the destitute. Definitely the forerunner of the modern fifth-wheel camper.