Left with their mobiles, Wang posted his predicament on the social media WeChat Moments, and within hours a friend's niece who lived nearby brought them 1,800 euros and helped them go through formalities to apply for new passports.

"You learn a huge amount by traveling," he says, "be it to do with geography, culture or nature. When you're getting about you really do have to find out about local customs and traditions and respect them."

Wang's interest in caravanning was piqued when he was on a business trip overseas in 2005. He spent a year designing the campervan and got a Chinese car company to build it for him, and it cost nearly 150,000 yuan ($23,200).

The vehicle has been a hardy workhorse and has even been near the roof of the world, Wang and his wife having traveled to the base camp of Qomolangma, on a trip to Tibet autonomous region for three times. During the first trip in 2007, the demands that the high altitude put on the campervan meant that each time Wang started the vehicle or drove uphill, his wife needed to inject oxygen from an oxygen bottle into the air intake of the engine.

Wang says that he was one of the first people in China to own a campervan, and that when he registered it he was told that there were no more than 100 in the country. By 2014 that number had ballooned to 21,000.

Caravanning is likely to continue growing in popularity, he says, but another owner, Zhang Guangzhi, 49, a retired entrepreneur of Beijing, says the domestic market is still a fledgling compared with Western markets, where there are far more caravan owners and campsites.

Zhang says he has just returned from a four-month road trip with his wife and son in the United States. He has written about his experience on a campervan and caravanning forum and his reports have attracted more than 6 million hits.

Like Wang, Zhang designed his own caravan, and an online name he once used encapsulates his feelings for caravanning: "Home on the road".

"It's a slow and gentle way of living," he says. "When I wake up and look at the views outside I can decide whether I want to get up."