Panda towbar (westfalia) stayed on the 100HP. Maybe it could have made it fit, but it would mean destroying the diffuser.
On my abarth I have an Italian towbar especially made for the Abarth. It only needs a very small cutout in the lowest horizontal part of the diffuser.
More info could be found in my "Topolino Grigio" thread in the 500 Abarth section.
gr J