Hi,
our slide-on camper is way less volume to heat than a CT, and we can seal it reasonably well if we want to. (It has all the 'regulation' vents for internal gas cooking to make it difficult at least to be overcome by the dangerous combustion gas Carbon Monoxide)
In the small floor area we found a radiant heater was in the way and also keeping the heat of nearby structural parts was difficult. We had to keep moving it around, not wanting to melt the fiberglass.
We did have a portable gas radiator, but it was a similar problem with radiant heat and being in the way.
A small (750W from memory) oil column heater, as would go under a desk, sat at one end of the walkway, but did nothing to keep the place warm. Just not enough heat. A bigger one would not have fitted.
A fan heater (1000W) did a good job, and we could blow the warm air the length of the camper and get a reasonable level of warmth throughout. It was always in the way though, as it needed to be at the door end of the walkway.
I ended up putting in a diesel heater in the luggage area out of the way, drawing cool air from the camper and returning toasty warm air near our feet. It draws combustion air from out side, and returns exhaust gas out there as well.
Yes, it was a substantial $$, but it is always there, Mrs loves it, so easy to turn on - just move the dial, burns very little fuel.
A gas unit is also made, built on the same principals which may be more practical for the warmer mainland climate, and it is a little quieter not needing a fuel metering pump, and is easier on the battery as it does not need a glow-plug start.
cheers
