Heat was going to be essential for living full time in the van. As far as I could see it we had two options, to get a diesel heater or a wood-burner, and I'm a sucker for wood-burners!
We had a lovely little wood-burner made by Julian the Gypsy (Well known in the hippy community) It was small enough to fit nicely in the van, but also large enough to fit decent size logs in and heat it efficiently.
Fitting the wood burner wasn't to difficult in the end. Basically it involved making a heat shield, cutting a hole in the roof for the flu and attaching a heat proof flashing.