Gary, is that the way the OEM made it? In that configuration those lynch pins are fuses.
Instead of cannibalizing a rope clamp what about just using a u-bolt. You can get those graded AFAIK.
They do make chain bolt for bolting a link directly, I'd check with trailer and boating places.
If I was you I'd probably just weld (or maybe bolt and weld) an eye to the trailer frame.
Maybe like this:
Then use a chain shackle to connect the chains to it. I don't trust those quick links and these are supposed to be /safety/ chains afterall.