It depends on whether it is a "need" or a "want".
My first RV was a class C diesel (6.9 liter international engine).
At 0 C (32 f) it would not start unless it was plugged into power for 3 hours.
The storage facility had no power. Therefore, if I wished to use the Rv in cold weather, a generator was a "need". That first generator (A Kipor 2800va TI) lasted 9 years. My woes started when I replaced it. In terms of hours of use--it maybe ran 100 hours a year. So it lasted 900 hours. I wished to replace it because it would no longer "throttle up" and would stall out with a load of 750 watts. In hindsite, a large solar upgrade would have been a better choice, and would have cost 1/3 what I have paid to date.