Hello Colinn,
If the oven is controlled by a proper thermostat, i.e. one that monitors the temperature inside the oven and modulates the gas flow to maintain the oven between an upper and lower limit, then the type of gas will have no effect on the actual temperature of the oven, only how quickly it heats up, and as Damian has pointed out the difference between Butane and Propane is not enormous, and if these gasses are used with the older gas pressures (Butane - 28mB, Propane 37mB) then there is no practical difference in heating performance.
What is not clear though is how accurate the controls on the oven may be. So it may be helpful to obtain an oven thermometer (From good cook shops) and then you can check the caravan oven and make your own adjustments as necessary.
There are a couple of other factors that might explain some of the apparent differences. The caravan oven has a smaller burner than a domestic oven, so the ability of the oven to recover temperature after a cold object is placed inside may be less than the domestic oven, it might also limit the ovens maximum temperature to a lower level. And the level of insulation around the oven may be less so it tends to loose more heat through the walls etc.