I've bought a camper/caravan MCB board from ebay (bargain £8) and an external socket. The external connector socket runs the power to the MCB which then distributes the power (via fused switches) to your sockets.... This will then 'trip out' should you have any poor earth connections etc.
I am happy to cut a hole in the bodywork it and fit socket... will probably go for an area near the back passenger side cupboard, will site the MCB box there too.