Too much bending stress on the bottom flange where you are welding. Better to put the stress in the stinger for any drop you need.
What I did was weld via GTAW a 2" receiver to a plate replicating the bolt pattern of the pintle, then weld a gusset to the bottom of the receiver and a flange plate match drilled to the two vertical bolts in the bottom plate of the bumper. Then a buckling gusset to keep it all together. 1/2" bolting plate for the pintle, 3/8" plate for the rest. All ASTM A-36 steel so it has good ductility. GTAW is far superior to ER70-S6 GMAW with 100% CO2 shield, don't ever use that process for a hitch. Dual shield with 75/25 or S6 with 75/25.
So 6 bolts hold my receiver to the bumper. All bolting is grade 8 with nylock nuts. Held 8k with 900 pounds tongue.
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