I looking at an alternative to a large natural gas generator and looking at
a 5 - 7kW gasoline powered job with gen-tran manual transfer switch.

If its raining I can't use the generator outside. Our outages usually occur
during approaching thunderstorms or hurricanes so running the generator
outside is not possible.

I'm considering putting it in my detached garage which is about 30ft from
the house and has the fusebox. The garage is 21 x 25 two car garage.

I'm looking at installing a 20"x20" auto shutter gable vent and placing it
behind the generator with a gable fan blowing outward. The exhaust will be
plumbed outside through a thimble and the garage door will be up an inch or
so to let air in. (~400sqin area) in addition to my soffet vents.

CO detectors will be installed in the garage in case of a build up of co.

do you guys think that setup will work and be safe?