My tinyhouse stays warm in the cold winter for sure. As long as I use the woodstove properly. But with a woodstove you have several hours without any heat being produced due to sleep so then the temperature drops but thats just fine in my opinion. But if you want to have a quick fix o this `problem` you can have a big pot of water on the stove that acts as a radiator during the night. Works fairly well but ofc depending on your insulation.
The wagon weighs app. 4 to 5 tons.
@Pupausis: That wagon you linked cant weigh that much. But I think you can get a real weight on it if you google around a bit. Looks like one of Dan Louche`s wagons but Im not sure.