I'm of the opinion that if you can buy new with the generator installed, do it.
Our first fifth wheel didn't have one and after a storm blew thru, no power for two days. And of course, a generator was not to be found anywhere locally. The only one we could find right away was the Honda 2000. That barely did it for us, but we still went out to buy a 4K later.
Now our latest 5er has the Onan generator built in and it is now one less thing to worry about or pack.
I think those 4k champions are a great idea if you don't have one built in. Not too heavy and works well. Down side is you have to remember to bring the gas. Keep in mind that if the power goes out area wide, gas pumps won't work either
But for boondocking it should be fine.