Is my hitch set up strong enough

[mrhino]

Hey Guys Im putting a hitch on my project. First the hitch I have was not made for this truck. Second the truck use to have a hydraulic lift on the back. The only thing left of that is a extension made from tubing welded to the bottom of the frame. It used to be a rectangle tubing but we had to cut a section off with a torch when removing the lift.

After I cut the mounting tabs off of the hitch(didnt align anyway). The hitch fits nice and snug againt the inside of the outside wall of the tubing. My question is: If I drill holes bolt it with four 1/2 bolts on either side would it be strong enough to pull, lets say a car trailer safely? the tubing does appear to be welded very well and all the way around. If you don't think it would be safe why and what should be change to make it so. thanks for your input