Last few times I bought the sanding paper separately myself (3 different grits, water sanding smoother and smoother) and then polished them to high shine with a paint polish and orange pad on my polisher, followed by a coat of Wax or paint sealant.
should be noted that this is to be performed as a last resort, and will have to be performed almost every year to keep the clarity (as you remove the protection on the lens by correcting them). But I am sure you knew this fact already. Aren’t your lights on the mustang only a year or two old?