Beretta makes a good pad in two thicknesses. Be careful in adding any pad, as often the unintended consequence is added cast, meaning pushing a shooter’s eye away from the gun. This may be okay; maybe not.
They are a bit pricey too.
https://www.amazon.com/Beretta-Gel-Tek-Shotgun-Protector-Thickness/dp/B009PTRXQG
