Rear Bumper Odd Question.

I am installing a new rear bumper on my 1973 scamp. The previous one was bent inward an inch or two. I tried to fit the old bumper mounts to the new bumper. The mounts are bent too far to fit. I found some replacements on Ebay. But,,, Has anyone just used the outer 2 bolt mount holes on each side of the car to hold the bumper. What I mean is cut the mount to only have the 2 holes that mount to the car and the 2 that connect to the bumper on each side.

I understand that it would not be crashworthy but neither would fiberglass ones. I figure I could save 20-30 lbs or more. Just a thought that I am considering.