I use this "Curt RV Bumper Hitch"
which mounts to my rear bumper. Recently, due to concerns expressed by others, I had the rear bumper reinforced (sorry I don't have any photos yet)... but what I did was have the existing welds ground down and redone. I then had four pieces of steel welded on a 45 degree angle between the rear cross member and the bumper itself. It's very strong now with no chance of tearing off due to torsion brought on by the weight and bouncing of the bikes.
I will post pictures next time I get the trailer out.
Mike, Sue, Sissy and Little Man
2015 Ford F350 Lariat FX4 6.7 CC DRW
2015 Eagle Premier 351RSTS