Hitch Height: if you think you're way higher than a 10" drop hitch scenario, then you'll probably tow very infrequently. In that case, shove the receiver all the way in!
My pin is behind the bumper and only on rare occasion did I think it was annoying. I made two keyholes to anchor the trailer chains but don't see to use them much. This is primarily due to the chains being too short!
Curious, why a round tube instead of square for the xmember? Notching a favorite hobby of yours?
I agree with Rusty, stick some gusseting about half way between the shackle bracket and the receiver hitch to tie the four pieces of long metal together. 3/16" material should be adequate.
Looking good dude!