I have yet to boondock in the cold, but I'm working on making it easily do-able. I have experimented with a couple of homemade hydronic heat systems, and am seriously considering one of those Olympian Wave 3 catalytic heaters. And in a similar, earlier thread on this forum, I saw a great idea for installing one inside a cabinet door; but in my case it would be installed on the rear bus door.
In my case, I could have a small hydronic heater near me, for personal heating, and the wave 3 for general heating, when required. (I have no basement plumbing to worry about). And I love pianotuna's idea of using a 'thermocube' and light for heating the fridge compartment.
http://www.thermocube.com/