Nope, never owned one, but, have looked at their design in big box stores. I considered one to add some auxilliary heat to our bathroom in our sticks and bricks, but, decided to go with, even in the S&B, a bigger, higher output, fan forced unit. I use fan forced in the RV to bring it up to temp, but, then rely on oil filled radiator types to maintain the temperature while we relax and sleep for the quietness the oil filled type provide.
It would appear, after reading the specs, that it may be OK for maintaining a temperature, as long as there are no drafts (not likely in an RV), for a very small trailer. The specs say:
"Heats Room Size – 130 to 150 square feet"
That isn't much space and, I would imagine, toward the larger side, in a draftless room of 150 square feet, it would take quite a while for much of a temperature rise.
Given the "draftiness" of RV units with slides and roof vents, and the abundance of windows in a trailer, the unit will prove rather anemic for heating an RV. To heat a medium sized RV with drafts and windows, a fan powered unit of greater than 475 watts would do far better (temperature rise and distribution) and for much less cost. Its claim of heating for 50% less $$$ is based on the fact that it has 50% or less of most other electric heater's output (475 watts vs 1000 to 1500 watts) and not its build or efficiency. If you like it for "safety" reasons (i.e., anchored to a wall and low current draw), then a couple may suffice in a small trailer (with no slides and one roof vent) to maintain the heat overnight, but, IMHO, a bigger fan forced unit would be the better choice and those can be had that are equally safe, though, not attached to a wall.
Just my thoughts on this particular heater, which was the orignal question.