I would not drill holes in the bumper.
Here's how I used a hitch off a Chevy pickup.
Welded 8 pieces of angle iron on hitch and U-bolted it to bumper.
I thought the bumper was strong enough to handle a bike rack. WRONG!!!!
Bumper started cracking off at frame. I squared bumper back up . I then welded rectangular tubing to the frame rails and to the first cross member ahead of bumper. Then welded two braces on the bumper between the U-bolts forward to the cross beam. The bumper hasn't moved since.