You should get rid of the flimsy bumper that is on there (imo) to do it right. It will end up twisting, caving in, or rotting out.
I had beefed up my original bumper on my last camper and put a rack on it. Loaded down and I though all was fine with the world... Going down the interstate, a guy pointed back to my camper..... I pulled over and the bumper had twisted down and the rack was inches from the road way. All of that stuff and the rack ended up in the camper.
I refused to go through that again. and cut the whole thing off.
2013 Forest River Salem Hemisphere SBT312QBUD
2001 CrewCab F-250 7.3 PowerStroke Diesel
SuperChip, BTS transmission, 6.0 Trans Cooler