Dave,
I did not think of using a hole say but switched to stepped bit for the front hole and it was not bad but the hole in the rear was a bear, maybe I changed the temper of the metal when I welded in the filler for the notched bumper, it was close to a weld, I dulled quite a few bits on that hole.
I did not think of using a hole saw and I have a bunch of them, bi-metal, good ones, duh!