DO NOT get a gas heater - they are only suitable for use in well ventilated areas.For heat get a bottle gas heater.
Using one in an enclosed space such as a cabin will result in carbon monoxide poisoning.
Fair point, although I was meaning 'use in accordance with the manufacturer's instructions in a well ventilated area etc'
Something like Baxi Brazilia heaters are available in LPG and are room-sealed.