I won't bother to detail about why I haven't been out in my un-insulated, unheated garage lately. But I did finally get to work again, trying to finish my bike trailer.
With the frame done I needed to attach the wheels, so I took two pieces of 3/4 by 1/8 inch steel strap, and bent them at the ends.
After bending these were welded to the back of the frame.
And a vertical bracket with a gusseted back was welded directly inboard from there.
The holes for the axle bolts are oval or elongated, so the wheels can be adjusted, the inboard bracket has vertical ovals and the outboard has horizontal ovals.
The wheels have been set "toe-in" for straight line stability.
Last thing left to do is work out a hitch.