We have an external socket, factory fitted, and run an extension lead from it. At various times this is used to power a small portable fridge, a tiny electric oven, a two-burner electric hob, or the light for the awning (which hangs from the awning ceiling pole). I would add that we don't run more than two together, and never the oven and hob at the same time!!
I can't find the thread on external sockets - but did read an article somewhere recently about someone who had just run the wire through the floor of the van and fitted a waterproof socket underneath. Was it in Practical Caravan???