[Mark7]

All electric heat is 100% efficient. (There is nothing going up a chimney or out a vent). It does't matter how it is delivered... fan forced, baseboard, radiant, infrared, etc. The only exception is heat pump systems which in some cases can double or triple efficiency, but lose efficiency the colder it gets outside.

The unit pictured could easily be a 4000-5000 watt unit (40+ amps at 120 volt) so it would not be a good choice to run at that voltage. Anything over 3000 watts should be run at 240 Volts, which is provided if you have a 50 amp service, but not very practical since it would use up most of your capacity.

Around my part of the country electric heat is the most expensive way to heat, unless it is subsidized or is controllable with some sort of load shedding equipment that can be controlled by the supplier.

That being said, if you have electricity included in your site fee, I guess you might as well take advantage of it! We often run the fireplace and /or a small 1500 watt ceramic heater in those situations, but we don't often stay in the trailer for extended periods of time when it starts getting below 50˚!