I remember when I first borrowed my parents first van years ago my dad had made up a short, maybe 500mm lead with a 10a male plug and a 15a female on the other end, just so he could plug in at home.
The van didn't have a battery and it was only used to run the fridge for a day or two before they set off. It did look a bit dodgy.
When I built my garage to keep the van in I had the sparky instal a 15a GPO on its own circuit, just for the van.
We have had friends stay overnight in the van here at home and this enables them to use the A/C or heater, depending on the time of year.
We never use it to stay in at friends houses so an amp-fibian is not really necessary for us, but I totally agree with everyone else.
240v can kill, don't take any chances.
Cheers,
Matty