OK made some more progress today. I gotta say those compound bevels are a PITA. I cut them by hand, since there is no way this brain was going to calculate how to do it otherwise.
Here's one side
And here's the other
This is how the end of the axle stubs looked. I later ran a small bead where the braces join the axle stub, mostly to keep water out, since structurally the axle isn't going anywhere.
Looking down from above. This is what you'd see if the bed were removed.
This is it in tilt mode.One thing that came back to me AFTER I had one side welded up. NOW I know why I had my self talked into just running the braces straight out from the frame, instead of angled, like I ended up doing them. When I went to dump the bed, the braces hit the tongue braces, preventing full motion.

Jim this is all your fault........ Just kidding. The logic of strength was good, but I needed to move the braces outboard about 1/2" for clearance. Sooooo, the grinder became my friend. I have almost full range now, but need a little more trimming. I grind off the corners where they meet. I actually got to thinking I will grind a little more and am might put some stops on the braces to save my paint later.
I did some more research on MIG welding and watched some more videos, and got a bit more education. I tried what I learned and got better results than I had before. I still have about 5-6lbs left on my solid wire spool, so when I can get some gas I will try to build something using only MIG.