It is necessary to have a generator in a 5th wheel, I know some have them some don't. We are looking to go to a 5th from our class a and we really don't use ours a lot now.
We travel FHU when possible and electric/water when absolutely necessary and so have never needed one.
We do have a portable (wheelable) 6,500 watt generator to power the house in the event of another hurricane. Charlie taught a lot of Floridians about generators.