A.
anwered by: canteau
It should, and Surly claims it compatible with Xtracycle systems and most of the Xtracycle parts will work on the Big Dummy, however Surly did make the Dummy Cargo Kit with the intension of it being used specifically on the Big Dummy so they may have included additional mounts on the frame not found on the original Xtracycle.
Surly has an instructional video here: https://youtu.be/shDVhWxAUBU