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.
I put a Honda 3000 in the truck bed bolted down with power fan vented metal cover. On longer stays I run my power cord up to the gen. Have a remote fob inside. Wife can even start it for hair dryer, micro, toaster, battery charge. Don't have to get out of my chair. Barely hear it.
When I need it I want it. All depends on how you camp.