Those 2 welds at the top (made by the fictitious HarborFreight MIG) don't look sufficient but the pintle hitch fell off first, so what the heck? Hey that thing's got no taillights! The D.O.T. officer is getting out his ticket book!
I could really stack a bead in this one with gaps this big. If you insist on doing this job yourself, first grind all the metal clean and shiny. no paint, no contamination. crank up the amps all the way on your hf welder. and starting at the bottom, run a bead. this lets the molten metal sit on a shelf. Then take a 4" angle grinder and grind it smooth and look for undercut(google it). "if" you dont have decent undercut, you should get another welder as many of us have said. but if you dont get undercut, and you want to be hard headed and weld it yourself anyways then weld the joint from both side and use 3/4" gussets and heavy angle iron brackets.
While you are welding (if you dont care about little Mary at the daycare) use gas shielding and not flux core wire and get the tip as close as possible for maximum penetration.
make sure you dip the tip of your mig in jelly so you dont crap up your tip.
then after you do all this welding and get your hitch on there, I want you to remember little suzie in the honda civic next to you.
and compare your welds to the ones on the hinge pins right above you.
(the safe ones) if you welds dont look like that then you shouldn't be doing it.
tip of welder closer to metal = more penetration and hotter weld
tip of welder a little further back = less pen and more filler weld
tip of welder in a pros hand = little suzie get to see mommy after work.
and good luck getting to the slack adjusters in your brakes.