I like your project!

The glue probably holds about 2,000 psi in shear, or 2,000 lb per square inch of bond surface which is in the ball park here. The sheet metal will begin to fail due to bearing stresses from 2 x 1/4 inch bolts under 1,000 lb. Those welds did not appear to have much area to them either.

The achilles of bonded joints lies in tensile peel of the joint. In tension the bond is fairly weak. If you can avoid this condition they will work real good in general. If there is tension then glue it and bolt (or rivet) it. The old belt and suspenders trick works wonders. BTW a pattern of 5 x 1/4 steel rivets (like on a dice) would probably rival the glue.

Kitz