I have a spare 3rd sitting in an axle I am gonna pull to weld it up.  Was planning on doing just what you sudgested.  My HF special wont do a weld like that but I have a Lincoln gas powered arc welder for it.  I had a buddy show me how to make it so you can pull the 3rd without disconnecting the brake lines.  I should have that done next week.

Today I moved my right rear shackle to get the angle correct.  Working on my rear bumper as well.  Lots of welding. I am gonna post pics tonight.