How do these two sections of the frame connect and stay put? I noticed while cleaning this one I can pull apart the frame right here, is it that bolt right next to it? Is it supposed to be through the other side of the frame and isn’t?
Welding a nut to the tab would work then drill a hole from the outside.
But this needs a welder.
You could drill a hole through the outer square tube and then through the tab, and bolt it in place. Clearance is tight to get a wrench over the bolt inside the tube.