Sorry I don't have pictures, but here's a description of what I did.
First, mounted 4 solid forged 1/2" screw eyes to the trailer, one at each corner to serve as anchor points on the trailer. You could also use heavy duty D-rings, or similar, for the same purpose.
Second, got 2 lengths of 3/8" transport chain, enough to stretch side-to-side, plus slack, one for the front set of anchor points; the other for the rear anchor points.
Third, added a screw-pin clevis to each chain so the chain slips through the loop.
Fourth, added a heavy angle bracket to the front weight bracket on the BX. TSC had a pre-drilled "stabilizer bracket" that I used, but it would be easy to make one from scratch.
To tie down the tractor on the trailer, simply pass the screw pin for the front clevis through a hole in the front angle bracket and similarly attach the rear clevis pin using the drawbar hole below the rear pto, then tighten up each chain with a load binder and you're ready to go!
Let me be the first to note that this setup doesn't meet the requirement to have the load held down with 4 separately secured attachment points, but it absolutely holds the BX in place, and it's way more than most of what we see on the road around here, which is mostly fabric strapping, and none too much of that. It could be converted to a full, 4 way setup without too much effort, but for my infrequent short hauls, this has been adequate so far.