What on Earth ever happened to discussion of these outstanding RV heating options that really have got it right: Propane and 12 powered ... ultra-low 12V power consumption and noise, vented, and hence with no moisture or combustion products into the interior ... combined with just sipping the propane.
These heaters would be especially great for long term drycamping:
http://www.ventedcatheater.com/heaters(Their design reminds me of the fanless vented propane heater in our 1969 vintage Class C motorhome from years ago.)