For the OP....I can't speak from experience since I am going thru the same learning process on my new TC, but when I purchased my camper it came with two of the bumper buttons from the PO.
And when I looked at how the buttons were deformed from the original shape and the holes where the turnbuckles attached were elongated it was an easy decision for me personally to decide against using them with our large camper.
Now I am sure they have served many people well over the years but I didn't feel comfortable trusting one bolt on a bumper to hold a little house on the rear of my truck driving down the road at 60 mph...heck I am still nervous at the thought of any tie down system working in a safe manner, but I guess I will overcome that as I try this out :)