Hi im selling what i believe to be the best heat source for your camper its the underfloor heater by riviera and these heaters are really rare to buy working and in good condition its on sale here follow link
The best, safest and quietest heater for a FC or TT is a small Oil Filled Radiator.
We used one in our small caravan and then in our FC and left on 27/7, it kept the units toasty warm, day and night.