As another kindly old grampa, could I suggest your plan be amended slightly?
Each of those RATs nests likely have child day care centers.
Those kids, while surely the spawn of RAT evil, are themselves innocent.
Could we remove them first?
Sterilize them if you must, to prevent passing on those RAT genes,
but the little eunuchs themselves might be salvageable.
I don't know how to answer that question. :)