My new Rockbros trunk bag was wider than I though so I modified this great adaptor to allow it to be more stable laterally as well as allow the hidden panniers to fold down and still be supported along its length.
V2 added (4) m3 nuts and bolts as well as thickened up P3. V1 works if you epoxy the locking shield but I had my first (with just superglue) pop-off and break the mount so I decided to up the strength for heavier bags.
The author remixed this model.
Added longer supports with wings to support wider bags