The total wattage of the generator depends on how many appliances you plan to use at the same time and how many watts those appliances use when on.
You want your generator to be able to handle the peak load with a 10% to 15% reserve. For example if your 5th wheel has two rooftop Air Conditioners; during the summer months you could be running both of them at the same time while using the Microwave Oven, watching TV while Blow Drying your hair. Your generator should be able to handle this wattage load with an additional 10% to 15% reserve.
The reason for the reserve is that appliances such as Air Conditioners use more wattage when they are starting up.
For more information read the answer I gave to the question below.
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