Re: Whole house fans
I once installed an attic fan through the end wall in a mobile home, for the same exact purposes and reasons as you're contemplating now, no flat section of ceiling or adequate attic space for any other type of exhaust fan.
The exterior was finished off with a louver and the interior was finished with a weather tight door. The fan was operated by switch only, no thermostat. It worked quite well.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!