I had mine done in a RV shop because I have no good way to access the top. Installation seemed pretty simple. Mine was replacing an existing powered vent.
They had to enlarge the hole to fit the new fan, and then install per instructions. The place who did mine didn't know about "Airstream garnish" (inside trim which fits the curve of the ceiling) so I called Fantastic and they sent me some Airstream garnish.
If you want others to be happy, practice compassion.
If you want to be happy, practice compassion - The Dalai Lama
1984 310 Limited Motorhome
Courtesy Parking (W/S/E/Wi-Fi) on I-5 in Northern California, 70 miles from Oregon border