Thanks for all the ideas guys.
"I can't upload a picture, but in your 2nd picture, I'm assuming the flat bar at the back is for your ramps. If they are supported only there, it should be strong enough to use as a tie down point and you should be able to weld the D-ring to that."
This idea, or a form of this idea, has crossed my mind. I am wondering in lieu of welding a D ring to the ramp support bar that I might be able to find a flat hook with a piece of chain attached to it that I can attach my load binder to. If it looks like that load could twist the end metal I could weld a strut from it across the top of the wood decking to the heavy piece of steel where the dovetail connects to the flat part of the trailer. That would not only help prevent rotation of the steel but would also help from pulling the metal at the rear of the trailer forward.
"Is there a reason you can't run your chain as shown in the picture? Just hook under the main frame, behind the bracket for your stiff leg and on up to the tractor? There isn't much difference between doing that and welding a D-ring on top of the frame."
I would like the attachment point to be further behind the tractor. You wouldn't have known this unless I had posted a picture, but the rear of the tractor is very close to the rear of the trailer. I have to do this to put the weight over the trailer axles and to keep the tongue weight under 2400 pounds.
As a side note, I was concerned about the weight on the axles so when I arrived at my destination after a 75 minute (most highway) drive I checked the temperature of the hubs they were only 98 degrees plus or minus a couple (70 degree day).
Thanks again,
Blane