@OP - My Yak looks exactly like yours. I don't think filing will make much difference one way or the other.

@fietsbob - It torques around the pivot point, so that the bike+BOB can maneuver around sharp bends in singletrack trail, which is what it was designed for (as opposed to running down huge hills at >30mph on pavement). If the BOB had a rigid hitch arm and pivoted instead at the mount adjacent to rear wheel hub (like Burley), then there would be no oscillation. One or two wheel isn't the cause.

I think Burley trailers are better suited for pavement-only duty for this reason. The Nomad is ~5 lbs lighter than a BOB with more volume (and weight) capacity (BOB conceals the fact that the Yak Sak weighs another 5lbs over the stated trailer weight of 13, for 18lbs total). The Nomad also makes a better off-tour trailer for grocery runs.