Space Heaters in a fifth wheel

We use two for cold weather and almost never use the furnace as it uses propane and we are usually on a hookup site. One is the standard little cube ceramic heaters, we use it during the day as it pumps out more heat and we only use it when we are around to keep an eye on it. It will heat things up quite nicely. We have a second Oil heater (looks like an old fashioned radiator). It is fan less has a lower wattage and in our opinion we feel safer keeping it on when we are not around or when we are sleeping. It does not heat up as fast or as hot but is good to keep it from getting too cold (at night or when not around), and the cube just gets used to top us up to a more comfortable room temp when we are near by.