It's a done deal with the grade 3 extremely coarse steel wool. Three bales of it.
Where I packed it, mice will never be able to access that space in the engine valley and around the knock sensors and fuel injectors.
I drove it 25 miles, no leaks.
They should have put a sign under the hood when they built that Tacoma, MICE WELCOME!
It is a great design, for a mouse house.