I prefer #110s, in the "runs" that lead to these holes. A couple of finger-diameter sticks crossed slightly above the trap and angling down and wedged through each corner of the trap, between the jaws, helps stabilize it until the rat is well enough into the trap to fire it. Shove those sticks into the muck on each side.
I get a nice mink now and then in these same sets. Rats in #110s have zero damage, too.
Jim-NE