When I fitted my last set of guards. I just put the guards in the correct place, drilled the bumper where the lugs are and then wing through the fixing hole's.
Could you not do that.
what ever you do is to drill the bumper ones first, then insert the protector pins as far as they will go then mark up you wing holes I say do it this way as the person who fitted mine a LR person did not do it this way and the pins that go into the bumper are only just in, I keep thinking one they will come out