Drive it periodically :)

This is my daily driver and that is one reason I am surprised to find a rat in there. That compartment has to get pretty darn hot.

Mine sits more than it's used so I expect varmints to check it out..:-X18
This time of the year I have birds sleeping on the wheels and frame at night..:-X21
As a daily driver you wouldn't think anything would want to setup home in there...:-hair

Take a couple of Bounce fabric softener sheets, twist them in the middle and put a piece of wire around them and attach them somewhere under the hood. Been working for 3 years with my tractor after the rats snacked on an ac hose.