I'm only aware of two bumpers that say they are rated for towing; Rock Hard 4x4 and LoD bumpers. Most the bumpers that have welded D rings will say they are not rated for towing, I'm sure it's the lawyers talking but none the less that is their stance. Rock Hard does make
brackets that work with Blue-Ox, RoadMaster, or Reese tow bars. In the case of those, the stress point isn't the bumper itself but the bracket, and the bolts. Both of those bumpers are in the $800+ range for a full width.