Oh dear, you are going to want to flatten me, but I'm afraid I can't help myself....
That looks
seriously wonderful, but I have one further little suggestionette, which is to do with the (oddly named) horse hook.
I think I am right in thinking that the ends were forged and "bent out" parallel with the solebar and then attached with a bolty-pinny thing. I think some suggestion of this would be the very finishing touch to your lovely wagon. In G1 I solvent Cambrian rivets with a flattened edge against the wire of the hook itself, I also file the tops off the rivet and then solvent a chip of hex rod on top to suggest the bolty-pinny thing head. In G3 you might need to try something a bit bigger or higher fidelity, no problem for a man of your cal-eyebur
I'll go quietly now...
Maybe
Simon