Protective Layer under Sensor Board

Is it allowed to use more than one protective layer for the sensor board? The regulations state under 2.1 that a protective layer may be applied only to the sensor board, nothing else. But is it allowed to use a protective layer not only on the sensor board front as indicated on the corresponding illustration, but also on the rear to protect electronics and the track?

[Question from a user moved here from another part of the forum]

  • In 2.1 “Protective layer” is talking about the brushes that sit between sensor board and track. No "Protective layer" is allowed any where else on the kit.