Work out the minimum generator size for your caravan, based on your biggest motor's starting surge plus everything else you'd run at the same time.
Compressor fridges and reverse-cycle air conditioners draw a short surge of roughly 2-3x their running wattage for a second or two on start-up - this surge, not the running load, is what actually determines the generator you need. This is a planning estimate only: check your specific appliance's data plate and your generator's continuous/surge rating before buying. For a full appliance-by-appliance breakdown of your daily power draw, see the Daily Power Usage Calculator.