I thought you were talking about welding part of a hitch. To weld jacks onto the frame is an easy weld. Basically all the weld is doing is holding the jacks onto the frame. The welds aren't having to lift a great deal of weight. There would be some stability stress but, that's a simple weld for sure. Yea, I would do my own welds on that for sure. I would grind the paint off to metal on the frame and jacks, weld those suckers on and hit it with some black paint. It's on there forever.
I welded the tongue jack on my motorcycle trailer. The trailer will be ripped to shreds before that jack would come off. I did that with a MIG welder. It holds with two Harleys on that trailer, no problem.
You don't need a machine shop to weld those jacks. Almost hobby welder, muffler shop, mechanic, should be able to weld those things on. Just hit it with a rattle can (black paint) after it's welded.