You are not considering climate control. You need a generator to run house air conditioning if you require A/C in your vehicle when you travel in warm climates and either:
Carry passengers back in the house.
Want to park without electrical hookups and use the house, and want it to be comfortable.
Sitting in the sun, RV is a closed box soaking up heat generated by sunlight striking the outside, like a closed up parked car. On a 70-80 degree day full sunlight will heat the inside of the RV to well over 90F within two hours if it is closed up.
Bump that to 90-100 outside, and it will go over 120F inside. You can cool it some by pulling outside air through the windows. That works well enough when it is cool outside, but not so well when it is hot outside. Even with A/C running, full sunlight on a hot day in a humid climate, you might be seeing temperatures over 90F, so you don't even want to try to do without A/C.
If you are only going to New England or northern Michigan, you might be able to get by in the summer without running the house air, but Virginia on south, and anywhere on the plains, you need that extra 13,000 to 15,000 BTUs of cooling capacity for much of the year, whether moving or parked, and you can get the power to run it only from a genset if you are not plugged in.
Tom Test
Itasca Spirit 29B
