It sounds like you have the same Carlson Floor Furnace in your trailer that we had in our 1960
Pacer. (Sorry, I can't find a picture.)
It struck me as being a rather nice idea--didn't use any electricity and ought to distribute the heat fairly well. However I never got around to taking it out for a thorough inspection and was a little nervous about it anyway. LP gas appliances and potential carbon monoxide sources have to be treated with great respect.
There is another thread about them on Airforums here:
The only documentation that we had for the furnace on our 1960
Pacer was a tag, shown here. Ours came with a key for a square shaft--much like an old fashioned roller skate key--for turning the gas on and off.