Unless the trailer has a long tongue on it, the short adapter is not going to work well, as the hitching point needs to be back almost in line with the 3ph arms I Match connection point. Otherwise, the moment you make even a modest turn, the trailer tongue is going to hit the rear tire on the tractor and I am mean going forwards or backing, because of where the pivot point is. I would suggest the correct mounts instead of a compromise.
The short adapter, whats to keep it from pivoting around the pin which secures it in place when any turns or backing effort is made?