As a play on the saying "size matters", that is true and something other than the Mini Van would have been needed to cross the Gibbs Road in Western Australia. However, we have done transcontinental trips in North America in a Classic Mini sedan with and without the custom trailer. The Clubman Window Van gave us all the space we needed for camping gear, spares, tools, cameras, computer, binoculars etc. etc. in addition to extra water, fuel and food stuffs.
Here is our Mini on our first transcontinental return trip in 2000 across Canada to Quebec and home through the United States. Photo (unfortuately lo-res) at Fort Randall Dam on Missouri.
Here is the restored/modified Mini and custom trailer which set out in 2006 south to Arizona, east to North Carolina, north to Maryland and home across the Great Plains and mountain states to British columbia.