You can also simply attach a round 6 inch PVC pipe with end caps and strap it to the top of the bumper. No drilling, no attachments, just a couple zip ties or bungie cords to hold it on.
Then use the metal bumper for hauling metal poles, fire pokers, BBQ sticks, or anything else made of metal and has pointed ends.
I've been using the PVC piping since we had our first pop-up camper.
You can see it clearly here on our first pop-up. I've used this same tube on every camper we've had, including our current fifth wheel. (although it is not on the bumper now, as my current fifth wheel does not have a "bumper" at all).
Later, on another travel trailer, I added a 10 foot long one under the trailer. I accessed it from the rear. It butted up against the axle, it was that long. Worked wonderful:
