Just as an aside - to be fume-free during warm weather - I see no reason to have any windows, or doors, or roof vents (except for a single powered vent) open whenever running an RV generator large enough to run one's air conditioner (even though the generator may be running for other reasons, such as battery charging). This is because with the generator running, coach comfort can be achieved via generator powered air conditioning instead of open windows or doors.
Doing this, just use the interior air pressure method that I mentioned earlier to keep all generator fumes out. It's easy and effective, even for those with extreme exhaust fume sensitivity. The single powered roof vent open to maintain the coach's interior air pressure also provides enough fresh air while all the other RV openings are closed up.