Wouldn't he have to kill a rat about the same time every day to get it to smell? Things don't really stink like death in less than a day, even under a hot sun.

I imagine he'd have to kill rats, let them simmer until they're just about to smell, freeze them at the state of almost-stank, and take them out to thaw before he goes to bed.

But where are the rat alarms to tell him when to kill more rats?