I installed a woodburner in my 4m caravan 10 years ago and never had any problem with it, but you have to keep an eye on the temperature when it is drawing. Once it is closed down its fine. After ten winters usage the only deterioration is the mild steel chimney which has become paper thin at the top. I am just fitting another chimney.
Its been brilliant and keeps the caravan dry throughout.
I mounted the burner about 8" off the floor on a chipboard plinth with quarry tiles on top. At the back and one side I used the metal tops from washing machines as heat reflectors. The woodburner is mounted approx. 6" away from either surface.
One little problem is 'cold draw', this happens in the lower few inches of the caravan, where the burner is drawing in air. This can make for really cold feet.
I am experimenting this year with a solar powered fan piping warm air down to the bottom of the caravan.
Best of luck
PixiePete
September 2010