We have this mounted on the wall in our open front bedroom. It is a Delonghi Micathermic heater. It can be mounted on the wall or on its wheeled stand.

It does not give instant heat like a vornado will, but if you turn it on and let it heat for an hour or two, it will keep a constant temperature. It has an adjustable thermostat and several settings. We generally use it on the lower settings.
It is totally silent and has no fan which is very nice in the bedroom. The unit does not get hot on the wall side, even though it is only about 2 inches thick. We have used this for 3 years now and it works very well for keeping our sleeping area warm.
We have it mounted where our TV would normally mount in the bedroom, and it plugs into the TV 120 volt outlet on the upper wall.
This likely is not sufficient to heat your entire trailer, but it has worked very well for keeping our bedroom comfortable. It is $50 on Amazon,
Amazon link but we bought two at an outlet store for $19 each. We've been very pleased with them. I use the other one in my garage at home.
Just another alternative to the usual fan heaters, ceramic heaters, and oil radiator heaters...all of which are also good.